A large proportion of London don't celebrate Christmas anyway do they?
The largest proportion of London is Christian, according to the last census. To be fair, that was 2011, so the dynamic has changed a bit.
Which I found pretty shocking, because the second highest is atheism and I was rather hoping that would have been the bigger number. Be interesting to see what it is at the next one.
Other religions do celebrate Christmas in their own way, it's just not a main holy day for them. Sikhs, for example.