- Having attended Hasmonean High School in London, David Mencer went on to spend a year of study in Jerusalem, focusing on Middle Eastern historical, religious and political culture. He was in Israel during the Gulf War of 1991, and was able to volunteer for a short time in the Israel Defence Forces.
- On returning to the UK, David attended the London Guildhall University, where he studied Politics and Government. He completed his final year dissertation on the vexed question of the sovereignty of Jerusalem within the context of the Middle East Peace Process.
- David initially went into the House of Commons in 1995 as a research assistant to Joan Walley MP, when she was the Shadow Transport Minister. He subsequently worked for a number of shadow ministers, working finally for Gwyneth Dunwoody, Chairman of the Transport Select Committee and President of LFI.
- As Mrs Dunwoody's political aide and, following that, her electoral agent, David orchestrated her 1997 General Election campaign in Crewe and Nantwich, where her majority was raised from 2,000 to 16,000.
- A short time after the 1997 General Election, David replaced his freelance political consultancy work for a full-time position as a Public Affairs Executive at The Waterfront Partnership. There, he was able to provide public affairs advice to a number of leading companies in the transport and food sector.
- David Mencer became the Director of LFI in July 1998.