There's a picture of one of these on Flickr, reg BNH 302 it is a "1949
AEC Regal with Whitson observation coach".
Dinky made the model from 1950 to 1954 under number 29f. In 1954 it got
renumbered to 280 and remained in the range until 1960. The later 280
models in boxes get the best price, look for the cream one with red
detailing and red hubs.