Turns out that Professor Michael Mendl, biologist and leading light at Bristol University Vetinary School, takes an interest in coins, as does Jerry Coyne, biologist and author of "Why Evolution is True." Prof. Mendl very kindly verified that this is a coin of the realm, and told me that his whole family are keen numismatists. His elder daughter is collecting Olympic themed 50p pieces, whilst his youngest daughter is the proud owner of a very rare Girl Guiding 50p coin, which celebrates 101 years of Girl Guiding in the UK.
I also understand that Mike's eldest child and son, has a Totnes pound note. I understand this may indeed be very rare, but it is way beyond my own field (inland piracy) and so I take little interest in the subject.