Thomas Babington Macaulay founded CMS Grammar School on June 6, 1859 and presided over the school with great distinction as Principal from 1859 to 1879 when he died.
Under Thomas Babington Macaulay, the school witnessed rapid growth and esteemed consolidation. He developed the CMS Grammar School into a famous school, and was reputed to be a stern disciplinarian determined to instil moral discipline in the boys under his charge. From the start he made it his priority to assist the boys in the development of their character and to prepare them for public service. This has remained the tradition of the school.
Macaulay's main pre-occupation, encapsulated in that of the CMS Mission, was to raise a bunch of boys who would be spiritually deep, morally sound and academically endowed enough to shape public opinion and raise standards anywhere they found themselves after graduation.
He got married to one of Bishop Ajayi Crowther's daughters, Abigail and from that union came a son, the famous Herbert Macaulay, leader of the Nigerian nationalist movement and founder of the first Nigerian political party – the National Democratic Party NNDP in 1932 and who later in 1944 co-founded the National Council of Nigeria and the Cameroons NCNC with Dr Nnamdi Azikiwe.
Successive Principals over the years had laboured tirelessly to keep those cherished traditions, break new grounds and set the school on a greater course.
The Rev Henry Frank Johnston (1834–1908) was an eminent Anglican Bishop  in the last decade of the 19th century and the first decade of the 20th.He was born 17 December 1834, youngest son of Colonel Johnson of Walbury, Great Hallingbury. Educated at Eton and Trinity College, Cambridge, from 1856 to 1858 he was a Cornet in the Royal Dragoons after which he studied for ordination at Wells Theological College. Following a curacy at Richmond, Surrey he was Vicar of High Wych,Sawbridgeworth and then Rector of Chelmsford. After this he was Archdeacon of Essex, before being appointed Bishop of Colchester in 1895. He remained Bishop of Colchester until his death in 1908.[
Isaac Oluwole (1852–1932) was a Nigerian bishop of Sierra Leonean and Egba heritage. He was one of the most prominent emigrants from Sierra Leone resident in Lagos during the second half of the nineteenth century. From 1879-1893, he was the principal of the CMS Grammar School, Lagos and was later ordained a priest. During his time, he was one of the most loved among his peers of clergymen. A reason which may have led to his recommendation as a bishop after a leading radical candidate, James Johnson, complained about the neglect of indigenous control of the Church of Missionary Society.
Isaac Oluwole attended the premier West African College, Fourah Bay, where he earned his bachelor degree. He was first among three students to obtain a bachelor degree from the school, which had become affiliated with the University of Durham. He later became the principal of the Church Missionary Society, Grammar school, Lagos, in 1879, taking over from Rev T. Babington. Macaulay, a son-in-law of Bishop Ajayi Crowther. He was ordained a deacon in 1881 and later became the assistant bishop of Western Equatorial Africa in 1893. He was ordained at St Paul's Cathedral, London on June 29 and was subsequently awarded a doctor of divinity degree from the University of Durham. His son Isaac Ladipo Oluwole studied medicine at the University of Glasgow graduating MB ChB in 1918.
He was born in Sierra Leone in 1836 to liberated African parents of Yoruba origin. Johnson enrolled in a Church Mission Society (CMS) school, then went on to Fourah Bay Institution, located in Freetown, graduating in 1858. He was a school teacher until 1863, when he entered the ministry. The CMS was impressed by Johnson's potential, and sent him to its Yoruba mission in Nigeria, first in Lagos and then in Abeokuta. He was unsuccessful as a missionary, perhaps because of his rigid morality, and in 1880 was instead appointed pastor of the Breadfruit Church in Lagos.
When the Lagos Colony was separated from the Gold Coast in 1886, the legislative council of the new colony was composed of four official and three unofficial members. Lagos Colony Governor Alfred Moloney nominated two Africans as unofficial representatives, Johnson and the trader Charles Joseph George.
In 1890, Johnson became assistant Bishop of the Niger Delta and Benin territories, holding this post until his death in 1917. He believed in a puritan, evangelistic Christianity, but was hostile to other aspects of European culture which he felt were not suitable to Africa.
The Rt Rev Frank Melville Jones, CBE, DD was an Anglican Colonial Bishop in the first half of the 20th century. He was born in 1866, educated at the Nelson College and the University of New Zealand and ordained in 1890. After a cuarcy at Holy Trinity, Cheltenham he went out to be a CMS Missionary in Onitsha. He was Principal of the CMS Training College at Oyo  In 1919 he became the inaugural Bishop of Lagos, a post he held until 1940. He died on 8 January 1941.
The Rt. Rev. F. Melville Jones was the pioneer Bishop of Lagos; or what in Rotarian parlance the Americans would prefer to style "The charter Bishop of Lagos."
Before his consecration and subsequent election to the exalted office, Melville Jones was the Principal of St. Andrew's College, Oyo from 1894 to 1907. He was indeed the one whose credit it was to have moved the college from Lagos to a more spacious area in Oyo town, Southwest Nigeria. He was highly regarded as a veteran school master and skilled administrator. Yet he was principally an Episcopal pioneer and explorer. Bishop Jones was a great church man, and energetic European missionary and educationist of high repute. Friendly in outlook, industrious and highly innovative, his handling of the affairs of the college was generally adjudged to be of superlative degrees. He repeated the same feat as the pioneer Bishop of Lagos. Yet, behind those seemingly tough Facade was a quiet man, frank in his comments, firm in his dealings, but open and accessible to his "subjects". He was uncompromising in the application of Christian doctrines to real life. He also had (perhaps because of his training as a teacher,) a peculiarity of assessing his workers (be it clerical or laity) and deploying them to duty posts to which they were best suited. In spite of that, he supervised tasks given by him and would sanction any erring staff without any hesitation.
It was during his tenure that the wooden bungalow building on the Marina that served as Diocesan office and Bishopscourt were erected. He operated the entire Diocese which stretched as far as Kano in the North and entire West and Mid-West as only one big Archdeaconry. In the area of spirituality, Bishop Melville Jones initiated and encouraged the nurture of prayer cells, Bible study classes, Sunday schools-which were veritable opportunities for teaching the largely paganistic society of his days. He stuck to the motto of WORK AND WORSHIP so tenaciously and taught at every opportunity undiluted, the Spartan principles of holy living, soberness and unflagging commitment to Christ.
CMS Grammar School had a most successful year under Revd J. S. Fanimokun, In November 1899, the register contained the names of as many as 112 boys, and the examination results were remarkably good. The colonial Inspector of Schools reported that "in the Primary Department, 91.7 per cent were proficient, and in the Secondary Department, 98.8 per cent. The school won twelve prizes in various subjects at the competitive exhibition of school work. Two of the boys were successful in the Civil Service Entrance Examination in December 1899, one gaining the first, and the other the ninth place: another passed the same examination in August; and in the Technical and Survey Schools Examination held in September the only successful candidates hailed from the Grammar School. "A pleasing feature of the year was the co-operation of 'old boys', some of them giving back to their school special prizes for proficiency in stated subjects.
The Revd Canon (later Professor) E. J. Evans, a scientist and well-known author of science books for secondary schools, who introduced the teaching of Science in the School, succeeded Revd Fanimokun as Principal in 1915. It was he who in 1919 composed the music of the School Song, which was later harmonized by Fela Sowande, an old boy of the School. On leaving the School, Canon E. J. Evans later became a Professor at the University of London.
In 1929, The Revd F. Watherton took over as Principal. During his tenure, some students in the school were successfully presented in 1931 for the new Senior Certificate Examinations. The Revd Watherton left the School in 1932 following his appointment as Principal of the new Igbobi College jointly founded by the Anglican and Methodist Missions. The CMS Grammar School again provided Igbobi College with some of its foundation students, the others having been drawn from Methodist Boys' High School, Lagos.
The mild-mannered Ven. (Dr.) J. Olumide Lucas succeeded The Revd Watherton as Acting Principal. Ven. J. Olumide Lucas, a great scholar, author, music composer, and theologian, left the school in 1935 on being appointed the Vicar of St. Paul's Church, Breadfruit. The boarding house has been named after him in recognition of his contributions to the progress of the School. He had been preceded by three expatriates, and was succeeded by yet another, The Revd Thorne in 1936 as Principal. Mr. Lewis, popularly known by the boys as 'Jeki' maintained strict discipline the School and won the respect of parents and the public. He did not hesitate in flogging errant boys. When a few boys from wealthy families became unruly, he expelled them from the School. It was he who introduced the preparatory class in the School by which boys drawn mainly from the CMS Girls' School were admitted and prepared for the entrance examination to the school.
He left in 1944, and subsequently became a Professor at the Institute Education in the University of London. Such was his commitment to the development of education in Africa that he ended his academic career in the 1980s as the Vice-Chancellor of the University of Zimbabwe. During his tenure as Principal, the teaching of Science in the School flourished so much that Science Tutors from other schools came to the CMS Grammar School for further training, and to use its excellent Science Laboratories. Some students came to School for the preliminary science course, preparatory to entering Yaba Higher College for the Diploma course in science. He was ably assisted in the teaching of Science by Mr. (later Professor) C.O.Taiwo, and Mr. C.A. Fawole, both of whom had read Science at the Yaba Higher College.
The Revd (later Bishop) S. O. Odutola succeeded Revd C.G Thorne in 1936 as acting Principal. It was he who expanded the Science Laboratories in the School
Mr. Lewis, popularly known by the boys as 'Jeki' maintained strict discipline the School and won the respect of parents and the public. He did not hesitate in flogging errant boys. When a few boys from wealthy families became unruly, he expelled them from the School. It was he who introduced the preparatory class in the School by which boys drawn mainly from the CMS Girls' School were admitted and prepared for the entrance examination to the school. He left in 1944, and subsequently became a Professor at the Institute Education in the University of London. Such was his commitment to the development of education in Africa that he ended his academic career in the 1980s as the Vice-Chancellor of the University of Zimbabwe. During his tenure as Principal, the teaching of Science in the School flourished so much that Science Tutors from other schools came to the CMS Grammar School for further training, and to use its excellent Science Laboratories. Some students came to School for the preliminary science course, preparatory to entering Yaba Higher College for the Diploma course in science. He was ably assisted in the teaching of Science by Mr. (later Professor) C.O.Taiwo, and Mr. C.A. Fawole, both of whom had read Science at the Yaba Higher College. During the World War II in 1942, those reading Science were evacuated from Yaba Higher College to the CMS Grammar School to complete their diploma course.
Mr. Lewis was the last of the great expatriate Principals of the School all of whom left indelible marks on it. He had been preceded by three expatriates.
The Revd (later Bishop) Seth Irunsewe Kale, who left in 1940 for St. Andrew's College, Oyo, which had been founded in 1896 by the Anglican Mission as a Teacher Training College. Under Revd Kale, the teaching of Science in the school continued to flourish with the recruitment of more science teachers and the expansion of Science Laboratories in the School. Kale House, one of the houses to which boys in the school are distributed, has been named after him.
Revd Canon (later Archdeacon) B.A Adelaja took over as Principal of the School in 1950 and remained Principal for twenty years. When he left in 1970, he had equalled the feat achieved by the first Principal of the School, The Revd Thomas Babington Macaulay, who also served for twenty years.
It was during the long tenure of Revd Canon Adelaja as Principal that the School, after years of careful preparation, moved in 1959 to its present site at Bariga, then virtually a virgin land on the outskirts of Lagos. Understandably, many Old Grammarians, who remained sentimentally attached to the old site at Odunlami, privately expressed their reservations about the School moving to Bariga.
In retrospect, the decision to move the school to Bariga was wise and justified, as the old site in Central Lagos had become too small and cramped for the School, which needed new facilities such as a good sports arena and modern Science Laboratories. All this was accomplished at the new site during the tenure of Revd Canon Adelaja, who will always be remembered for his contribution to the fame and physical development of the School during his tenure as Principal. It is in recognition of this that the School Hall was posthumously named after him.
T. A Ojo went on to become the Principal of the Birch Freeman from 1972 - 1976 and later of Igbobi College from
Happily Chief I. A. Olowu, who had taught in the School for many years under Canon Adelaja, returned as its Principal from Igbobi College in 1972 and served until 1984. He was an inspiring Principal who loved the School and the boys. Even in his 80s', he continued, almost without fail, to attend the Annual Founder's Day Service at the Cathedral. He was a great tutor of Latin and Geography, who did not brook any intellectual indolence from the students. He also took a keen interest in the career and progress of the boys after they had left the School. It was during his tenure that the school excelled in sports, winning many national and international laurels.
Popularly known as Brother Jem, he was the Maths tutor from the late 70s into the 80s. He never spared the rod and whipped boys who had been unsuccessful in a Maths test with his left hand.
The Ven. Johnson Onayinka era as Principal was the era of re-construction and massive restoration. There was the herculean task of restoring confidence in the general public that the school could still be what the founding father(s) wanted it to be. Hardly did any day pass without one ugly incident of street urchins and rapists, hoodlums and robbers fighting themselves and shedding blood in the full glare of the school community. Prayers and the assistance of law-enforcement agents did the magic. The ugly experience of the unenviable yesteryears and lingering sour taste that it left in the mouth were scaring indices for an administration poised to resuscitate slumbering destinies. The 'war within' did not help matters. But the all-conquering God was there to pull down the "Walls of Jericho."
Then came the young, pragmatist and an old boy - The Venerable Tunde Oduwole who, from 1st September 2005 assumed duty as the 23rd Principal of the School. He began an era of consolidation and aggressive reformation. Under him, and within only three years, the school got a 50-seater Luxury Bus, began the building of the Chapel from DPC level and dedicated it for worship on the 150th Founder's day Anniversary - the first ever in our 15O-year history.
There was also the relocation of the Administrative seat to the ground floor of the historic high-rise multi-storey Science Block.