Profile: Len McCluskey, general secretary of Unite

As the threat of strike action by fuel tanker drivers looms over the Easter break, Radio 4's Profile charts the career of Len McCluskey, the left-winger who became general secretary of Unite in 2010.

As the UK's biggest union and the Labour party's biggest donor, Unite is often in the headlines - many generated by its leader. Len McCluskey courted controversy by raising the prospect of strikes during the London 2012 Olympics and was roundly criticised by both the Coalition and the Labour party.

He has been an outspoken critic of Ed Miliband's leadership despite having played a key role in getting him elected.

Profile presenter Mukul Devichand asks what does Len McCluskey stands for, charting his journey from white-collar worker on the Liverpool docks to the most powerful trade union leader in the country.

This edition of Profile was broadcast on BBC Radio 4 on Saturday, 31 March 2012 at 19:00 GMT.

Listen again via the Radio 4 website or download the Profile podcast.