They joined Gillian Shephard, the former education secretary, to provide the three character references required for the Conservative Party's selection process. In September, the party's London members will choose their mayoral candidate for next May's election.
Tory officials denied that Mr Major's endorsement signalled that William Hague would support Lord Archer of Weston-super-Mare, who faces a challenge from Steve Norris, a former transport minister.
Lord Archer and Mrs Shephard were both members of the so-called "East Anglian mafia" who lived near Mr Major's Huntingdon constituency and became close allies - although Mr Major dashed Lord Archer's hopes of a ministerial post. The millionaire novelist met Cooper through his sport and charity links.
The Archer bandwagon received another push when Edward Lister, leader of Wandsworth Council for the past seven years, agreed to be his running mate for the deputy's position.
Lord Archer said he was "delighted that one of the most respected council leaders in Britain has agreed to stand as my deputy".
But Trevor Phillips, the television presenter who hopes to become Labour's candidate for Mayor, seized on Mr Lister's policies in Wandsworth, where he was criticised by police after seeking to recruit householders to patrol the streets as unofficial crimefighters.
"Now we know the truth - Jeffrey Archer is simply the front man for the hard-faced ideologues of the hard right," said Mr Phillips.
Meanwhile, Richard Branson, the Virgin boss, said from Shanghai that he was considering standing for mayor.