We're doomed! Mr Mainwaring's last stand found in BBC vault

The pilot episode for a sequel to Dad's Army featuring the last performance of Arthur Lowe as Captain Mainwaring, one of Britain's best-loved comedy characters, has been returned to the BBC archive after 20 years.

The pompous old muddler's swansong comes in a pilot episode for a sequel to Dad's Army. Called It Sticks Out Half a Mile, it was a little-remembered radio spin-off about Mainwaring's attempt to restore a neglected pier. The show was recorded in 1982 but never broadcast, out of respect for Lowe, who died of a stroke just weeks later.

The planned series was eventually recast, with Bill Pertwee reprising his Dad's Army role as Warden Hodges in place of Mainwaring's bumptious bank manager, and ran for 13 episodes.

The original pilot disappeared from the BBC archives, and has only now resurfaced after its creator, the veteran sitcom writer and producer Harold Snoad, discovered a copy at home.

The half-hour episode featuring Lowe is significant for several reasons. Not only does it boast the actor's last recorded performance, but periodically he can clearly be heard slurring his words - a symptom of the narcoleptic disorder that he was suffering from at the time.

The pilot is more amusing and poignant than the Pertwee version. In it, a retired Mainwaring is forced to beg for a loan to finance his unlikely pier venture from his sceptical bank manager - none other than John Le Mesurier's Sergeant Wilson, his former deputy.

Mr Snoad, who sent the episode back to the BBC following one of its periodic appeals for the return of lost archive material, explained: "I came up with this idea about Captain Mainwaring wanting to buy a pier. After the war, he had moved to Switzerland where he had been working in a cuckoo clock factory, but had decided to return to England because the climate didn't agree with his wife's chest.

"I rang up Arthur Lowe and he finally said yes, he'd like to do it. Initially, the idea was to do it for TV, but the BBC suggested it would work better on radio."

Though Lowe delivered a typically well-timed turn as the pompous Mainwaring, newly humbled by his subservience to Wilson, his failing health meant that the recording of the pilot was not without its difficulties.

"Arthur was suffering from narcolepsy, and he would start to doze off part-way through the recordings," said Mr Snoad. "We got it in the can in the end, but before we could transmit it, Arthur sadly died."

That a version of It Sticks Out Half a Mile did finally make it on to the radio was largely down to the enthusiasm of Lowe's widow, Joan. The programme eventually came off the air a year later, after Le Mesurier's death. A year or so later, Mr Snoad persuaded the BBC to commission a TV comedy play based on the same premise. Walking the Planks starred the late Michael Elphick with Richard Wilson in the bank manager role, though the names of their characters were changed to avoid upsetting the Dad's Army faithful.

It failed to make a full series on BBC1, but in 1987 it re-surfaced finally asHigh and Dry, a six-part sitcom on ITV, again starring Wilson, this time alongside Bernard Cribbins. This really was an end-of-the-pier show: when viewers complained about stagey-looking seaside sets the series was swiftly axed.