For example, lilac bulldogs are born black but dilute twice: once by the chocolate gene and once by the blue gene. The bb gene mutates from black to brown and the dd gene mutates from black to blue.

The pet, named after Vinnie Jones, is a £2,500 pedigree blue lilac French bulldog and is five months old. The 20-year-old self employed gardener said: 'I was out walking the dog by myself.