Range from the cheapest removal of a chimney breast £560 (Shape Design & Build based in W3) to the dearest removal of a chimney breast £580 (Right Build Group based in W11).
Comparing builders estimates for removing a chimney breast gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
What to do - Get rates and quotes to remove a chimney breast in W12 by posting a job with HaMuch and we will send it to builders in W12.

"Remove internal chimney breast in two rooms in downstairs flat that likely requires structural support after removal"
W4
"Remove chimney breast"
CHISWICK