Officers from Norfolk Constabulary are appealing for information in relation to a theft at Station Road, Dereham.
The incident occurred between midday on Wednesday 9 December and 3pm on Friday 11 December 2009.
The offenders gained entry to a paddock by cutting the gate chain and then stole an Ifor Williams horsebox trailer.
The trailer has an aluminium frame with plain unpainted wooden sides and had also just been fitted with a new wooden floor.
Officers would like to hear from anyone who may have noticed anything suspicious in the area between the times stated or from anyone with information in relation to the suspects or the property stolen.
Contact PC Ian Plews at Reepham Police Station on 0845 456 4567.
Alternatively call Crimestoppers, anonymously, on 0800 555 111.