Best known and utterly reliable is Motorcycle Funerals run by the Rev Paul Sinclair, a huge character and a national treasure in his own right.
“Why,” he asks, “should those who love bikes be last seen in an automobile?”
Motorcycle Funerals – motorcyclefunerals.com. Ring: 01530 834616. Based in Leicestershire, operates UK-wide.
There are also some hearse trailers out there pulled by trikes.Trike Funerals — http://www.trikefuneralsuk.co.uk/
The Rev Paul and others also provide bicycle hearses. Google bicycle hearse and then ring for details.