Ray Lewis was an inspirational black community leader who appeared to have a golden touch when it came to tackling under-valued and under-motivated children from the ethnic minorities.

A former parish vicar in the East End of London and a junior prison governor at Woodhill jail, Milton Keynes, Mr Lewis, 45, had the perfect credentials to deal with difficult youths when he became executive director of Eastside Young Leaders' Academy in 2001, which he predicted would educate Britain's first black prime minister. The 80 boys who attended the academy underwent military-style drills and physical activity with academic work and appeared committed to the disciplined regime, staying for sessions after school and at the weekends.

A string of senior Conservatives beat a path to his door in the East End to see at first hand how he was working to turn young people from disadvantaged backgrounds away from violence and crime with a prescription of "tough love" that chimed with new Tory thinking under David Cameron. He also symbolised the change in the Tory party under Mr Cameron, who was keen to show that black youth leaders could be embraced by the new Conservatives.

Mr Lewis was Mr Johnson's most symbolic appointment, a high-profile black community figure with a radical approach to social problems. The Mayor, and those around him – the key advisers who were close to Mr Cameron – knew he was taking a risk when he appointed Mr Lewis to the high-profile post on a salary of £124,364 in charge of young people in the capital. Mr Lewis was appointed without a proper vetting process.

The Mayor and Mr Cameron were assured by Mr Lewis's public record. The Mayor's official website continued to say last night that Mr Lewis was "also a trustee and governor of the Petchey Academy in Hackney and a Justice of the Peace", although the Justice Department had denied he was a magistrate. It also emerged that Mr Lewis had been suspended as a priest, although he denied all knowledge of being struck off.

He was born in Guyana in 1963, an English-speaking former British colony in South America with one of the poorest economies in the region, racked by ethnic tensions and poverty. He prospered after coming to Britain to study and he obtained a degree in theology and pastoral studies at Middlesex University.

He became a civil service administrative officer and a clerk in holy orders for the Church Commissioners in 1990. He is married to Pamela, with three daughters, and gave the pressure on his family over the sleaze allegations as one of the reasons for his decision to quit.

Mr Lewis's resignation is also a blow to the position of black role models. Lee Jasper, Ken Livingstone's race adviser, was a fan of Mr Lewis. But Mr Jasper was also forced out of office by sleaze allegations.