Yeah, they at least pronounce aluminium like they spell it. It's not a "Leicester" piss take.
https://m.youtube.com/watch?v=uYNzqgU7na4
TLDW; We have multiple different root languages in English city names, and you are only thinking one dimensionally, with the Roman Latin root. Cirencester is a good example, pronounced how you might expect while further north the town names get more germanic, and eventually Scandinavian.
The video helps it makes sense.
It's a funny example but to be fair to the British that also happens in other Germanic languages and it also happens a hell of a lot more in Romance languages.