London doesn’t have any monopoly on them, either. Two villages near me: Debach and Pettaugh. Give them a go…
DEBB-ich and PETT-oh? 
I’ve always heard it pronounded Marleybun. Brother’s lived in Twickenham for twenty years and he concurs.
Any country where “Cholomondely” is pronounced “Chumley” has forsaken all pretense to using English pronounciation, anyhow.
Any administrator that can’t spell “pronunciation” should be sacked 
Close, but not quite 
Deback and Pettoff
Rubbish
How about Deb’ch (ch as in church, not loch) and Pett’r?
When I used to work at the microwave radio site in the village (it’s that tall mast behind the old church), we called it Deb-atch, with the emphasise on the first syllable.
Maybe it’s becorrse I’m a Londoner - well, I was born about 2 miles from Marylebone and my Dad’s a lunnuner, and how I was brought up saying it is:
“MARRY-lu-bun”. I’ve heard people in London saying “Marly-bone” and it grates. But I suspect my pronunciation is now archaic.
Same as Holborn: “HO-bun”. No L.
When I asked some locals when I was living in London, the majority said it was something like “Marrl-uh-bone”.
The Brits would have you believe that they know how to speak English better than us Americans and Canadians and whatnot. They’re lying - silly people can’t quite figure out the “only as many letters as needed, and preferably, ones that represent the noises you’re making” bit.
as a member of Marylebone Rifle & Pistol Club, I often hear other members saying “Marly-bone”, which I dislike. I always go for “Marry-le-bun”.
So what I’ve learned is: however I pronounce it, someone will think it’s wrong.
Another West Londoner chiming in with a " fuggedabout the ‘y’ " opinion.
Actually forget about all that crap with the ‘short e’, the ‘almost schwa e’ etc etc.
Bob. Marley.
Marley. Bob.
Marleybob.
Marleybone.
And then you just imagine we’ve displaced the ‘y’ because we’re funny like that. But it’s simply ‘Marleybone’ as in ‘Bobmarleybone’.
I never did get around to recording that .wav (mainly cos I couldn’t find the charger for the only MP3 player I have with a voice recording function).
But the more I say it to myself, the more I think that both the “Marry-luh-bone” and “Marleybone” versions are correct, or at least both equally incorrect. Imagine a sort of hybrid of the two, but the “y” part kind of gets smeared somewhere between the first and last syllables. MARR(y)l(y)bone. Er, you need to hear it really.
However saying that the first part is like “Marry” is not quiet right - it’s not a short “a” like in “marry” but a long “a” like in “market”.
last try then bugger it
Debatch
Pettow
Debb’tch and Petter, at a guess.
Both just about there (Debach is an almost-rhyme with ‘cabbage’)