Mr Lilley's use of the executive aircraft will raise eyebrows in a party still reeling from sleaze allegations and questions about its links with big business. It will further fuel controversy about the leadership election which has seen all the contenders mount expensive publicity efforts. The Tory contest for the first time has used techniques more familiar to a general election, with candidates sending out messages on videos and glossy brochures.
Mr Ashcroft, 51, made a pounds 200m fortune from building up the ADT burglar alarms and car auctions group. He aroused suspicion in the City by moving ADT to Bermuda and cloaking the company's dealings in secrecy. His abrasive personality, coupled with a refusal to answer press questions about his company's share transactions, led to criticism.
In 1991, he was accused in acivil action by a major Canadian shareholder, a company called Laidlaw, of false accounting and manipulating ADT's share price. He denied the allegations, which were later dropped.
He has developed extensive interests in Belize, the former British colony in Central America. He acquired citizenship and became Belize's ambassador to the EC, a post which gave him diplomatic immunity. Today, he is based in Boca Raton, Florida.
This is not the first time he has sought to curry favour with the Conservatives. A close friend of Denis Thatcher, he once sought the party treasuryship but was rebuffed by Lord McAlpine, the outgoing treasurer. During Margaret Thatcher's premiership he sponsored the Crimestoppers initiative and Wandsworth City Technology College in south London.
John Fraser, a spokesman for the Lilley campaign, confirmed Mr Ashcroft had donated his plane. But it was not loaned directly to Mr Lilley but via his adviser - Lord Archer. "Michael Ashcroft lent Jeffrey Archer as a personal favour an airplane for three days. This was used for Peter Lilley's regional tour."Reuse content