Dear Mr Cornwell.
You have got all my family scratching their heads as to your riddle. I have written down lists of types of horse,i.e. pony, mare, colt Etc. and famous such as Copenhagen, Marengo Etc. and drawn a complete blank. Therefore my best attempt ignoring this part is “Merryman” or happy person. If this is wrong may I ask one favour. Is the answer(8 letters) one word or two, his surname or both. When you can get round to it a new Starbuck would be nice.
Best wishes,
Mike Walker, Worcester. UK.