Chris Rennard was once regarded as one of the most powerful political figures in the UK that you had never heard of.
While that is no longer the case - allegations about his behaviour towards female activists having thrust him squarely into the public eye - his contribution to the Lib Dems over the past 25 years cannot be overstated.
The 53-year old Lib Dem peer, who is now at the centre of an internal party row, was one of most respected and feared election campaigners of his generation.
As campaigns director and then chief executive, he oversaw a host of stunning by-election and general election victories for the party between 1989 and 2009.
The extent of his achievement can be summed up by a quick look at the parliamentary arithmetic.
In 1987, before he took on a national role with the SDP-Liberal Alliance, it had 22 seats. Twenty years later, the successor Lib Dems had more than 60 MPs.
He has served under a series of party leaders from Paddy Ashdown to Nick Clegg and been feted by all of them.
Charles Kennedy once described him as a "quite extraordinary figure" while, in 2009, Mr Clegg said he was "utterly loyal, hard working and dedicated to the wider good of the party".
He was credited with honing the strategy of "community" or "pavement" politics.
This involved a relentless focus on local issues and targeting of key voters as well as shrewd mobilisation of resources, both human and statistical.
Lib Dem by-election victories - in places as diverse as Eastbourne, Ribble Valley, Newbury, Christchurch, Eastleigh, Littleborough and Saddleworth, Winchester and Brent East - were the stuff of legend and led to claims by opponents of dirty tricks.
The Lib Dems, whose motto at the time was "where we work we win", were accused of saying different things in different parts of the country but this did not stop them claiming victories over both the Conservatives and Labour.
One of three brothers, Chris Rennard was brought up by his mother after his father - a dentist - died when he was only three.
He was educated at the Blue Coat grammar school in Liverpool, before getting a 2:2 degree in politics and economics at Liverpool University.
He has spent virtually his entire professional life working for the party.
He first became involved in politics in his home city of Liverpool - traditionally a Labour stronghold - as a teenager in the late 1970s.
Starting out handing out leaflets, he then cut his teeth working on David Alton's successful by-election campaign in Liverpool Edge Hill in 1979.
Four years later, he helped re-elect the Lib Dem MP in a different constituency in the city when working as his party agent and his star continued to rise.
Chris Rennard met his wife, nursery teacher Ann McTegart, while she was working on a Liberal campaign in a neighbouring constituency. They married in 1989.
Awarded an MBE in 1989, Lord Rennard lists his interests outside politics as cooking, wine and France.
Although he stepped down from frontline politics in 2009, citing the pressure of managing a diabetic condition, Lord Rennard has remained an influential figure behind the scenes as well as working for a number of other organisations including the Local Government Association and Action on Smoking and Health.
He was made a life peer in 1999 but relinquished the whip voluntarily last year after a number of former and current activists accused him of making unwanted sexual advances and touching them inappropriately, allegations he has always denied.
After an internal report found the allegations could not be proved beyond reasonable doubt, Lord Rennard is seeking to retake his seat in the Upper House.
But party officials have said he cannot do so until apologising for "distress and offence" caused to the women concerned.