My friend David McClean, who has died aged 73, was a gifted teacher and historian who taught in the London borough of Havering for 37 years. He was always somewhat unconventional as a teacher and never took himself too seriously, but his historical and political knowledge were impressive.

Dave was born in Donaghadee, County Down, to Samuel McClean, a local government officer and a mayor of Newtownards, and Gertrude (nee McWatters), a legal secretary.

From Regent House school in Newtownards he went to Queen’s University Belfast, gaining a history degree in 1970. He then took a PGCE at Stranmillis University College.

Dave was appointed a history teacher at Royal Liberty school in Romford, in Havering, in 1971. At the time, I was also starting out as a history and politics teacher at Abbs Cross school in Hornchurch, in the same education authority. Four years later Dave joined us as head of history. He was still at Abbs Cross (now Abbs Cross academy and arts college) at the time of his retirement 33 years later, by which time he was head of humanities.

In 1985 he married Elizabeth Radley, an English and drama teacher at Abbs Cross. They had two daughters; they later divorced.

Although somewhat to the left of me politically, Dave supported me loyally when l became the GLC member for Hornchurch in 1981 and in my two attempts as Labour candidate for the same seat in the general elections of 1983 and 1987.

In 1982 I introduced Dave to Ken Livingstone at County Hall. Ken had a fan for life, and Dave commented as to how different Ken was from the way the Daily Mail usually portrayed him.

Dave was passionate about Northern Ireland and always keen to discuss its politics, but he was no supporter of either Ian Paisley of the DUP or Gerry Adams of Sinn Féin. He steered a sensible middle course and always hated violence. When the UK became involved in the Iraq war, Dave resigned from the Labour party.

Dave enjoyed sport, coaching generations of students in football and tennis, and he, himself, played both sports well into his fifties. A regular attender of St Andrew’s church in Hornchurch, he took his Christian faith very seriously.

After retiring in 2008, he enjoyed keeping up with friends, watching sport, his church activities and reading his hundreds of history books. He also had a great love of quizzes.

He is survived by his daughters, Rebecca and Jessica.