In reply to Gordon Stainforth:
> Yes, on the one occasion I visited it for a few days many years ago everyone pronounced it ‘blow’.
Hardly surprising as that's the way it's pronounced (or very close to that anyway - there's no closing of the lips to suggest a 'w' at the end.)
Also, the name derives from 'Fontaine belle-eau' (clear water source), and anyone who's ever wrestled with the subtle (to British ears) differences in French pronunciation of 'on', 'en' and 'an' will know that the French are often very particular about their vowel sounds!