Lucky find at my local 'car-boot' sale today - a plastic model of the coach used in the Queens silver jubilee celebrations in 1977. Cost £16 - a bit more than I would usually spend on a second-hand model but heck its nice to treat yourself sometimes. It's actually quite a reasonable model; history of the coach see (http://www.londononline.co.uk/monarchy/Royal_State_Coach/),
The coach is good and the right sort of size, however the horses are a little small. A closeup of the coach, with one of my Garde Suisse figs in to show how close a match for size it is for 25/28mm figs.