The UK's Working Title Films is developing an untitled family film based on newcomer Billy O'Brien's short film The Tale Of The Rat That Wrote.

The story of a rat's adventures in a dark, Dickensian world combines live-action, animation and the animatronics effects from the blockbuster Babe. O'Brien is to adapt his 1999 short himself, with the film's producer Ruth Kenley-Letts also on board.

The original film follows a rat caged in a rodent emporium where experiments are carried out. After unsuccessful escape attempts - one includes being captured by a mob and forced into a rat-fighting contest - he realises he has to confront the owner of the emporium.

Working Title has also had to postpone Johnny English, its comedy spy film starring Rowan Atkinson as a hapless Foreign Office agent, although the company still aims to get the production up and running. Johnny English had been expected to shoot early next year at Pinewood, which would have housed the production for Bond 20 at the same the time.