Built by Wendolene’s Father to protect her, Preston had faulty circuitry and eventually turned evil. He developed a plan to rustle sheep and sell the wool in Wendolene’s shop, before going even further and killing the sheep to make his own brand of dog food. [1]Finally thwarted by Wallace and Gromit during his eleventh rustle in as many Months [2] he was upgraded into a completely different dog, although Wendolene said he was “just like he used to be” not to hurt Wallace’s feelings. [3]
Later on he unfortunately turned evil again and teamed up with Rhett Leicester, Wendolene’s tenant, to try and take down Wensleydale cheese. Once again Wallace and Gromit defeated him and he was mashed into pieces by a crushing machine. [4]
Later still he really was just as he used to be and helped Wallace and Gromit out with their pet care business. Gromit was convinced that he was still bad, but in the end was proved wrong as Preston actually saved his life. [5]
[1] A Close Shave
[2] Grand Adventures and Glorious Inventions
[3] A Close Shave
[4] The lost slipper/curse of the Ramsbottoms
[5] Every dog [has] its day
