Welcome to the forum. You should find a wealth of information on this site relative to equipment, techniques and other details about crow hunting. One problem, however, is that most of us are based in the USA rather than the UK. While crows are similar worldwide, calls, techniques and other details will vary.
YouTube has lots of good info on your side of the pond. Watching many of them, I am jealous that you apparently do not need as much camouflage as we do. A few of us (me include) have also reported on the amazing effectiveness of the FF5 flapper imported from your neighborhood. Good luck and stay in touch.
Demi
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The man who thinks he can, and the man who thinks he can’t are both right.