I know the Guernsey laws but, I believe it is illegal to sell any fish that have been speared in mainland England.
I think this has somthing to do with some archaic law based around using harpoons!
Spearo Dave was (is)the expert on this sort of thing and it has been discussed several time before, I had a quick hunt but couldn't find anything...
In Guernsey you cant sell anything caught from a boat unless the boat has a license but, you can sell any fish caught from the shore whatever the method - however the sale must be documented & declared to the tax man!
Would be interesting to know as a good friend of my parents said she could sell my fish if I ever caught any decent sized silvers to a restaurant.E Being I only caught my first two silvers the other day I haven't but thanks for bringing this up. I feel some research is in order.