At the time of the phone call, Boris was working for the Daily Telegraph in Brussels - having previously been sacked by the Times for making up quotes.

Guppy, who was later jailed for fraud, was angry at a News Of The World journalist and wanted to have him attacked. Having contacted some heavies, Guppy had asked Boris to use his journalistic contacts to find the reporter.

While Boris appears to do little to deter Guppy during the phone call, he is clearly concerned that the journalist in question will not be too badly beaten up. He also expresses concern about covering his tracks.

Boris has claimed that Guppy was 'in cloud cuckoo land' at the time and that he never did - nor intended to - follow through his offer of help. The tape shows Boris was willing to co-operate nonetheless.

Despite Guppy's apparent plans, the journalist was never beaten up.

When asked to comment on the recording, Boris Johnson's spokesman told Dispatches: 'This was a colourful story from almost two decades ago. It was of little or no consequence back then - and has no relevance whatsoever now.'