Zaccheaus Ososanya was one of those who played a seminal role in the establishment of the Institute of Chartered Accountants of Nigeria. 

Early Life and Education
Zacchaeus Oludayo Ososanya was born to David and Jeminah Ososanya on 14th May 1924 at Sagamu in the Ijebu-Remo local government area of Ogun State. When he was young, he aided his father with work on cocoa farms and did minor carpentry work. Ososanya began his primary education in 1932 at St. Paul's School, Sagamu, and continued at St. Augustine's Catholic School, Itesi, Abeokuta. In 1940 He spent a year at Ijebu-Ode Grammar School before leaving for the Baptist Boys' High School, Abeokuta where he joined in class IV and graduated in 1943.
Mr. Ososanya struggled to get to the United Kingdom in 1948 only to find that securing a place with an accounting firm was extremely difficult. Undeterred he eventually succeeded in being hired by a firm of Certified Accountants: Messrs Hyman Freedman & Co. of 92 Gray's Inn Road in West Central London. Mr. Ososanya was able to get through all his examinations by June 1952.

Career
Ososanya started work in Lagos on 1st May 1944 in the Military Audit Section of the Federal Audit Department where he worked for a period of two months before securing a permanent appointment as a third-class clerk in the Judicial Department. There the tough and much dreaded Magistrate C.N.S. Pollard would mentor him. Ososanya remained in the Department until his departure from the United Kingdom in 1948. 
Upon returning to Nigeria after the completion of his studies Ososanya began working with the then Western Region Production Development Board (W.R.P.D.B.) as a stores accountant. By early 1954, he was the organization's acting Chief Accountant. In September 1954 Mr. Ososanya would resign and commence professional practice on 1st October 1956. Like Akintola Williams he undertook this task even though it meant directly competing with established expatriate firms.

Legacy

Ososanya was one of those who played a seminal role in the establishment of the Institute of Chartered Accountants for Nigeria (ICAN). In August 1959 he was invited to become one of the foundation members of the Association of National Accountants of Nigeria prior to the formation of ICAN. Ososanya accepted the invitation and would serve for more than thirteen years on the Council of the Institute. He became the President between 1968 and 1969.

Sources:

A Short History of the Accountancy Profession in Nigeria by Musliu Alibaba