The Helm Telemotor steering pump was taken from Hamilton's (Irvine) Ltd, on Rose Farm, sometime between Tuesday 27 December and Wednesday 28 December 2011.

The pump, which is valued at approximately £6000, is cube-shaped and was a light green colour but most of the paint has come off over time.

Officers are appealing to anyone with information about the theft to come forward.

PC Neil Soulby, of Selby Rural Safer Neighbourhood Team, said: "I am appealing to anyone who saw any suspicious activity in the area of the farm around the time of the theft to contact the police or Crimestoppers with information.

"The pump is very heavy and would have taken two people to lift and a vehicle to transport it away from the scene.

"I would also appeal to anyone who has been offered this item for sale to get in touch."

Anyone who can help the police with their investigation is urged to contact North Yorkshire Police on 101 - select option 2 - and ask for PC Neil Soulby.

Alternatively, Crimestoppers can be contacted anonymously on 0800 555 111, quoting reference 12120004512.