Foxfish, certainly this is my understanding of uk laws.Do you remember SpearoDave? He was an active and poinant member.. Brithish spearfishing team, shop owner etc.. anyway he repeatedly quoted that it was illegal to sell any speared fish in the UK.
As I remember the key word was 'harpooned' something to do with some bygone law relating to poaching Salmon but nevertheless a law. Of course I have no idea if he was (is) right and that is one reason I an interested in johns comments.
I paraphrase here but basic law is:
No spearing license is required
No spearfishing in freshwater
No restriction on breathing apparatus
No spearing freshwater fish in salt water ( one can only assume trout and salmon)
No selling any speared fish
No restrictions on day or night spearfishing including by torchlight.
No spearfishing of crustaceans
I'm certain somebody may have something to add to the above, but it is the rules which I abide by