Wilma, racing as Cavecourt Blue, came in last in a race at Poole Stadium, Dorset, on Tuesday night, but demonstrated pace that eluded her during the race to outrun her handler, jump a wall and squeeze through railings to freedom.

Efforts to capture her in the car park failed, and later sightings around local stores and in nearby traffic have heightened concerns for her safety.

Nervous disposition

Her trainer, Mrs Jo Burridge, said: "The longer it goes on the more worried I am getting."

Police, walkers and postmen have been looking out for Wilma, who is wearing an orange jacket with the number five and a muzzle. She is said to be of a nervous disposition.

Mrs Burridge said: "She could be completely exhausted at the moment and laid up somewhere. She could have injured herself and be in trouble."

Wilma's flight from human mastery echoes the heroic run of the Tamworth Two, the pigs Butch and Sundance who struck a blow for animal rights last year when they escaped from an abattoir.