Insurance conundrum

[Kermit power]

I'm a middle-aged bloke in Surrey. Clean licence, one minor accident 3 years' ago, 13 years' no claims (protected, hence still having it), office worker, etc, etc....

I just got an insurance quote for a Saxo VTS as a fun car for under a grand. The cheapest TPF&T quote on Confused.com was from AXA at £262.

Reasonable, I thought... How much would fully comp be, I wondered?

AXA was still the cheapest, and the quote rocketed from £262.... Er... Down to £222.

Can anyone explain how fully comp can be cheaper than third party???