Despite often attacking senior staff at the News of the World, Regan was popular with readers and wrote his pieces in line with the newspaper's view.
In April 1981, Regan obtained transcripts of telephone calls made by Prince Charles in Australia to Lady Diana Spencer, then his fiancée.
In addition to revealing their intimate conversation, Charles could be heard making disparaging remarks about Malcolm Fraser, then Prime Minister of Australia, and about some aspects of Australian culture.
In 1989, Regan founded Scallywag magazine in South Dorset when the lure of journalism drew him back from his retirement in Butterfly World in Lodmoor Park, Weymouth.
Scallywag started to attract a loyal readership, although the major newspaper distributors refused to handle it (a situation Regan regarded as tantamount to censorship).
Scallywag became a news story in itself in 1993, when it stoked a rumour that John Major, then Prime Minister, was having an affair with Clare Latimer, who was a freelance cook who helped with state dinners at 10 Downing Street.
Clare Latimer later claimed that "Mr Major used her as a "decoy" to prevent what would have been the more politically damaging exposure of the affair he had with Edwina Currie from 1984 to 1988.
Scallywag limped on, but a 1994 story about Conservative politician Julian Lewis led to another series of libel actions, which the magazine lost comprehensively.
"[4] Regan was married and divorced twice; he had five daughters, one of whom (Charlotte) stood as an Independent in the 2001 general election in Regent's Park and Kensington North.