Before Bob Mortimer made his name as a star contributor to BBC television's yarn-spinning series Would I Lie To You? it looks like he was honing his fictitious storytelling skills on late night radio.

It has been a not particularly well-kept rumour that Mortimer used to phone up late night radio DJ Iain Lee regularly over a five-week period in the guise of someone called "Keith" and spin various flights of fancy about his friends and his family. 

The genuine identity of Keith was never revealed at the time, although his distinctive north-eastern accent was probably a strong clue. In one call he talks about sports videos and filming his nephew Harry, who is a "very fast runner...he's fifteen and has done the 200 metres in 34 seconds. It's a good quality run that." Lee replies: "I think I could do it faster." Keith adds music to videos he has shot of him running, so Lee suggests the Chariots of fire theme. Keith replies: "My wife likes U2." 

In this clip of Mortimer when he was on Taskmaster he talks about phoning a radio show talking about his fast runner son.

If it isn't Bob, however, it is possibly Keith Bridgewood, who was at school with Bob and appeared as his mystery guest on Would I Lie To You? There is a Twitter account @SportVideoKeith – "Keith from SportVideo, fast running video producer, uncle to Harry, husband to Ann. Contact for Meadow Horse/WigWam & Co bookings" which includes the name Keith Bridgwood (sic).

The radio recordings have been circulating for a while. There was a compilation on YouTube but since this story first appeared it has been taken down. Possibly a coincidence, who knows? Here's a link to a clip that remains below.

Bob's – if it is Bob – contributions recall the antics of comic legend Peter Cook, who used to call up late-night radio stations pretending to be a lonely Scandanavian fisherman called Sven who was from Swiss Cottage.