Does the author (Jezhotwells) have the ability to release it under a free licence, if
s/he
wishes?
No but if they put it on permanent display in a public place the photo would probably be totally fine under UK freedom of panorama law.
I suspect a court would hold that the set of "cakes" is disjoint from the set of "objects on permanent display", and thus that a photograph of cake can never benefit from freedom of panorama.
#nomnomnomnomnom
Chris