Kumquat can be spelt cumquat! I had no idea, my world view has changed completely.
I was glad to be correct when I stated that the plural of roof was in fact roofs though (which is why I had got the dictionary out in the first place). It is one of those abnormalities I had remembered, but when no-one else seemed to have heard it I was worried that I'd remembered it wrong. The terrible thing is that Word allows you to spell it with a v apparently, naughty Word. Although blogger doesn't, so well done blogger, though it does want me to change cumquat, but I won't I tell you!