I use old bread from the baker the crows love it and after a few days you can shoot at them.
I put some dead birds on the bread and it works very good.
It works in Denmark,but maybe your crows is different in taste.......
Here in Denmark we mostly use camo net and some good Realtree camo close with gloves and mask.
I mostly shoot crowes and a littel bit of pigeon,it aint like in England.....wish it was.....