Trying to hold back tears, Lisa Leeson, who sees her husband for one hour a week in his prison in Frankfurt, read at a news conference in London a letter from Mr Leeson addressed to the British media.
It concludes: "I have made all possible information available to the SFO (Serious Fraud Office) in recent weeks and at present, the British authorities seem happy to throw me to the wolves. All I want to do is come back, take my punishment and get on with life. I'm a British citizen after all. Please please help me."
In the letter Mr Leeson says he did not steal any money, but admits he exceeded his authority in dealing in derivatives for the bank in Singapore. "I acted unwisely and exceeded my authority but never with the intention of enriching myself."
Mr Leeson's dealing account clocked up potential losses of hundreds of millions of pounds, causing Barings to collapse owing its creditors around pounds 900m.
His lawyer, Stephen Pollard, said the plea was triggered by an indication from the Serious Fraud Office last week that it was likely to turn down an offer from Mr Leeson to allow himself to be interviewed under caution from his jail.
"Mr Leeson is sitting in a cell in Germany waiting for them to arrive with their tape recorders ... he has evidence that a crime was committed over which the British authorities have jurisdiction."
Mr Pollard explained, however, that the SFO had indicated it did not wish to take up Mr Leeson's offer of an interview.
The SFO has the powers to extradite Mr Leeson if it feels any of the offences leading to the collapse of Barings were committed in the UK. So far, though, it has indicated it does not have evidence which warrants an extradition application being made for Mr Leeson.
Yesterday the SFO said: "The events which led to the collapse of Barings bank predominantly occurred in Singapore." The SFO statement does not say why it has not to taken the option of an interview with Mr Leeson.
"We have told them that he would answer all questions fully," Mr Pollard said, "and we have even sent them a script showing what he could talk about. All his knowledge goes to the heart of the issue. It looks to me like the SFO has lost the stomach for a fight."
The Singapore authorities have put in an extradition request for Mr Leeson containing 12 charges. These are being contested by Mr Leeson.
Mr Pollard said the Singapore authorities had given the SFO next to no assistance. "They have even refused to give the SFO a copy of the extradition request which the SFO have now obtained from my office."
Mr Pollard said a trial in Singapore, which could result in a minimum jail sentence for his client of 14 years, would never get to the bottom of why the bank collapsed because its terms would be too restrictive.
"If Mr Leeson came back to London all sorts of people might be embarrassed but either we find out what happened in the collapse of Barings by holding the trial or we don't. There will be no contribution to our understanding if the trial goes ahead in Singapore," he said.
Mrs Leeson, now working part-time in a tea shop, said her husband had been bearing up under the circumstances. She said she could not really describe her ordeal since leaving Singapore with her husband just before the collapse. "I have managed to cope, although I cannot believe what is happening."Reuse content