It’s not that “cester” is pronounced “ster”, that would be bonkers. Instead this is a bracketing problem due to the existence of the name “Chester”
It’s (Worce)(ster), (Leice)(ster), (Glouce)(ster), etc. Once you see that, the pronunciations are mostly quite intuitive.
British place names: A guide for confused Americans
If a town has "cester" in its name, that bit is just prounounced "ster"
Worcester = Wooster (with a short 'oo')
Leicester = Lester
Gloucester = Glosster
Frocester = Froster
Alcester = Allster
Bicester = Bisster
Towcester = Toaster (yes, really)
Although I must admit, the modern pronunciations are actually due to rebracketing in the first place… from an Old English word that eventually became “Chester” lmao
“ceaster” meaning “settlement” became both “-cester” in placenames and “Chester” as a name and placename itself.
yeah no one would be confused about “Leicester” if “Chester” wasn’t a thing, but it is and therefore people can’t figure out how many syllables are in British place names.
also people mispronounce “misled” all the time by analogy to words like “tousled” and “grisled”, brains are fun
