Officers have released images of the stolen items, which were taken overnight between Saturday 12 November 2011 and Sunday 13 November 2011, from the Maltings Industrial Estate.

The horsebox, which is silver and maroon, has the words Harness Racing emblazoned across the front and also had two number plates attached to the back. The plate FY06 YBR was visible at the time of the theft, with the plate T5RYT underneath.

The owner has also added two tie rings to either side of the trailer, which is valued at £3,000.

The stolen generator was mounted on a red base with the serial number 3701252AC1C00.

Police are appealing to anyone who witnessed the thefts or has any idea where the stolen items are, to get in touch.

PC Sally Smith, of Selby police, said: "I am appealing to anyone who witnessed any suspicious activity around the Maltings Industrial Estate at the time of the thefts to get in touch.

"The incident has obviously caused a great deal of inconvenience to the victims and we are keen to help them get their property back.

"If you have been offered either of the items for sale, or know where they are, please contact the police or Crimestoppers with information."

Anyone who can help the police with their enquiries is urged to contact North Yorkshire Police, on 101 - select option 2 - and ask for PC Sally Smith, or Selby Police.

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