Released in March 2010 this is one of a pair of wagons, based on models seen in Hunts of Marlow - a ironmongers shop in the Buckinghamshire town. The shop also sell some model railway items.
This particular model will be in a grey colour and the running numbers will be in the one-twenties - ie from "120" to "129". See item 87a for the red/brown wagons. Hence it will be possible to collect twenty wagons - ten of these red plus ten of the red ones!