In agree with OTC the DEFRA code or practice comes from the GWCT they are the ones that are testing snares and advicing DEFRA. Even new traps sent to the CSL for testing and approval for spring traps order are not field tested, they are only compared to the standards of what is already approved.
I remember many years ago when I was keepering in North Devon we had Glens rocking eye snare come from the GCT for us to test and what a great snare it was to, and again now the GWCT have sent out breakaway snares to keepers to test when all they need to do is consult the people that have been usin