Mr Leeson, currently in a jail in Frankfurt awaiting extradition by the Singapore authorities, offered to confess to charges in the UK carrying a maximum sentence of seven years if the Serious Fraud Office would seek his extradition to Britain.
If he were to be extradited to Singapore, Mr Leeson faces 12 charges, including forgery with intent to defraud, false accounting and cheating. If found guilty there, he could face a prison term of between 14 and 84 years.
The remarkable offer represents a direct challenge to the beleaguered SFO, which until now has been reluctant to pursue the matter. "We have effectively offered our client on a plate," said Stephen Pollard, Mr Leeson's lawyer, "but we have no alternative. We would rather have our man hung in England."
Mr Leeson, 28, fled Singapore in February after his bets on complex financial instruments went spectacularly wrong, crippling his employer Barings with debts of around pounds 900m.
Mr Pollard, of Kingsley Napley, has for several weeks been trying to persuade the British authorities to seek his client's extradition. The SFO has powers to do this if it has evidence of a crime over which it has jursidiction. The SFO admits it has such evidence, but last week told Mr Pollard it considers it would be more appropriate for a trial to be held in Singapore.
Mr Pollard indicated that his client would plead guilty to at least four charges of false accounting, an offence which carries a maximum sentence of seven years' jail in Britain. These include one that suggests he tried to mislead Coopers & Lybrand, Barings' auditors, into thinking that a pounds 50m loss he had made was in fact a debt owed by a US investment firm.
He would also plead guilty to at least one other offence, details of which Mr Pollard declined to give, and possibly two offences over which the British authorities may have jurisdiction.
"This is the highest-risk strategy I have ever embarked upon," Mr Pollard said, "but up to now there just has not been the political will to extradite him here."
Mr Leeson's offer comes as the publication of the Bank of England's report into the Barings affair is expected early next week. Last week his wife, Lisa, appeared at a press conference, at which she read from a letter from her husband and pleaded with the media to help him avoid "being thrown to the wolves".
Mr Pollard has offered the SFO, which has been investigating the Barings affair since the merchant bank collapsed in February, an interview with his client under caution.
After discussions with the SFO he has also sent it a written script of the subjects his client would be prepared and able to cover in the interview. He said: "I have never been in a situation where a defendant has said, 'I will give you a full and frank interview under caution' and then have the police say, 'Can we have it written down first?'."
Asked if Mr Leeson was prepared to plead guilty if he was extradited to Britain, Mr Pollard said: "The inevitable conclusion of what we have said is that he is ready to plead guilty."
He went on to give some details of the offences which his client's likely guilty plea would cover. He said that Mr Leeson's evidence would not be sufficent to implicate anybody else at Barings of fraud.
However, the SFO, having read xswhat Mr Leeson is likely to tell its investigators in any interview, has indicated it sees a trip to Frankfurt as of limited value.
This weekend the SFO said: "Private and confidential discussions have been taking place between the SFO and Kingley Napley. We are not prepared to conduct these discussions through the press."
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