Spencer was born in Woolwich in 1969 and lives in the borough with his wife Liz who is having a rest from her career as a journalist to look after their two children, Kate and Arthur.

Spencer's father was a local veterinary surgeon who died when Spencer was 11 years old. Spencer attended the local independent School, Colfe's on an assisted place and went on to get degrees in Politics/Economics and Britain in the European Union.

He has worked as a Betting Shop Manager, Customer Services manager and for the Office of Fair Trading but in 1996 he discovered a passion for teaching and started work as a teacher at Kemnal Technology College in Footscray. He returned to Colfe's as a teacher of Economics nearly four years later, shortly after the birth of Kate. Spencer is currently Head of Year 10/11, in charge of guiding students through their GCSE years.

His achievements as a teacher include the fact that he taught the first ever students to get A* grades at Mathematics GCSE at Kemnal and in 2003, 3 out of 5 of his Business Studies GCSE students were placed in the top 5 nationally (out of 61,000 students).

Spencer was elected as a councillor on Greenwich Council in 2002 and his son Arthur was born shortly afterwards. He loves rugby and plays for the Old Colfeians fourth XV most weekends, where his sense of honesty and fair play is often commented upon.