I would recommend that you telephone the Rural Payments Agency of Defra and tell them you have a CPH number and want to let them know you will be racing across the Channel. I would be surprised if they give you a new number.
This is the number to ring 03000 200 301 and select Rural Payments Agency.
NEW INFORMATION 19/03/2026
A CPH (County Parish Holding) number with the final four digits beginning with a 9 (e.g. 12/345/9xxx) are valid for keeping under 50 birds. Racing pigeons however it is only valid for racing within GB. It is not valid for racing to the EU or Northern Ireland.
A CPH with the final four digits beginning with an 8 (e.g. 12/345/8xx) is valid for racing pigeons across the channel from the EU and Northern Ireland.