Grey bullfinch

We had a new visitor, we have had very rare visits of a male bullfinch (a handful of visits over 3 years) and yesterday we were surprised by a new visitor, something that was clearly a bullfinch but grey.

My question is that is a female bullfinch grey or brownish, as books suggest?

Being in central England, I don't expect to see anything exceptional so we assume it was a female bullfinch and it is just the natural variation of the species.