General Sir Peter Inge, 58, Chief of the General Staff, who has taken over as caretaker Chief of Defence Staff, is thought by many in the Ministry of Defence to be the most likely candidate to take over the pounds 112,083-a-year post.
Admiral Sir Jock Slater, 55, the Vice Chief of Defence Staff, who is noted for his charm and military acumen, is also favoured by some in the MoD.
Another candidate is Chief of the Air Staff, Air Chief Marshal Sir Michael Graydon, who is seen as the least likely to be appointed.
Sir Peter Harding, who served as Chief of Defence Staff for 15 months and was expected to continue for another year, resigned on Sunday night after the News of the World published a five-page report of his affair with Bienvenida Perez-Blanco, 32, while she was married to Sir Antony Buck, 65, former Conservative MP for Colchester North and sometime junior navy minister in the Heath administration 20 years ago.
In the report, for which Miss Perez-Blanco is said to have been paid handsomely (although not quite as much as the pounds 200,000 suggested in some reports), she identified the unnamed man cited in the subsequent divorce as Sir Peter and said that Sir Antony had found out about their affair after discovering love letters.
The most questionable part of the episode is held to be the way that the newspaper decided to verify the story by deliberately attracting Sir Peter to a lunch at the Dorchester Hotel, with journalists armed with cameras on hand to record the meeting.
Yesterday, Sir Antony was reported to have sold his side of the story to the Sun for an undisclosed fee. He issued a statement expressing his sadness over the break-up of his marriage and for Sir Peter and his family.
Professor Robert Pinker, the Press Complaints Commission's privacy ombudsman, would not say yesterday whether details of Sir Peter's affair should have been published, or whether he would carry out an investigation.
The payment obtained by Miss Perez-Blanco from the News of the World, with the assistance of publicist Max Clifford was not in breach of the commission's code of conduct, which rules out rewarding criminals. No calls complaining about Sir Peter's treatment were made.
Sir Peter, 60, has been married for 39 years and has four children. Sir Antony married Miss Perez-Blanco, 30 years his junior, in 1990 but the marriage broke up last September.
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