Among the appeals featured tonight is a crime that took place in Frinton-on-Sea on Thursday 27 August. A Post Office van was making a routine delivery when the guards were attacked by armed robbers. Police believe four men were involved and are anxious to trace a white Sierra Sapphire and a black J-reg Alfa Romeo. Both cars followed the van until it was abandoned in a nightclub car park about seven miles away. Crimewatch UK will be showing two artists' impressions of the hijackers and reconstructing events in the hope that a viewer might remember where the cars went next.