Get a general licence to show certain species of captive bred birds in competition (licence GL14).
This licence lets you publicly exhibit and competitively show certain wild birds that have been lawfully bred in captivity. A bird is considered to have been lawfully bred in captivity if its parents were lawfully in captivity when the egg from which it was hatched was laid. You must have documentation to prove this.
This licence doesn’t cover the birds listed in part 1 of schedule 3 of the Wildlife and Countryside Act 1981 (it’s already legal to show these birds if they’ve been bred in captivity).
You don’t need to apply for this licence but you must meet its conditions and follow its instructions.