Cambridge supporters' group Cambridge Fans United has revealed that manager John Taylor's father Roger has become its 400th member.
The trust, which is the club's third largest shareholder, aims to secure a seat on the Abbey Stadium board and has so far raised about £100,000.
"It's great to have John's dad on board and it really wasn't stage-managed for him to be number 400," CFU chairman Nick Pomery told the Cambridge Evening News.
"It's another little landmark for the CFU, and now we are pushing on towards the 500, with the longer-term ambition of becoming a thousand-strong.
"Some people might say 400 isn't a huge membership, but it is more than 10 per cent of the football club's regular support.
"And we now hold 123,000 shares in United, which makes us the third biggest shareholder.
"Our membership compares very well with those of trusts at other League clubs, except at some clubs which have been threatened with closure."