From the Animal and Plant Health Agency (APHA) on Wed 2 Feb 2022.
Private Vessels - Boats and Aircraft
Only transport companies that have been approved by Defra may be used to bring dogs, cats and ferrets into Great Britain under the Pet Travel Scheme (PETS). These animals must also travel on an authorised route.
Animals may not be imported into Great Britain on private boats or aircraft, unless traveling from Ireland. Pets can only come into the UK on a private boat or plane if you’re travelling from Ireland.
For the latest information on approved transport companies and routes, please visit the PETS website at https://www.gov.uk/take-pet-abroad/approved-routes or ring the PETS Helpline on 03702 411710 (open Monday to Friday – 08.30 to 17:00 UK time). Please note that route lists shown on the PETS website are regularly updated and you should check before you book that you have the latest list.
Private vessels – Channel Islands
I can confirm that there is free movement for animals travelling within the UK, including the Channel Islands. Therefore you will not require any documentation in order to transport your pet under the Pet Travel Scheme. I would, however, suggest that you contact your chosen carrier to check whether they have any further requirements as often a health certificate is requested in order to transport your animal, this documentation is not part of the Pet Travel Scheme.
Please be advised that whilst there is free movement between the UK and the Channel Islands, it is prohibited to bring a pet into Great Britain on a private boat from another country. We therefore advise that you may wish to keep a ship’s log, noting which ports you have entered in order to avoid problems with port officials on re-entry to Great Britain.
If you were to encounter problems whilst out at sea and, for example, had to make an emergency stop in a French port for repairs, your dog would require quarantine on re-entry to Great Britain. We therefore recommend you have your dog prepared under the Pet Travel Scheme (PETS) to avoid such risks.
Refuelling, private aircraft.
Please be advised that while it should be possible for a private aircraft to land for refuelling in Great Britain (subject to the airports agreement) any dog or cat travelling on said aircraft will not under any circumstances be allowed off the vehicle.
If the dog in question was to disembark from the aircraft, this would be deemed an illegal landing and would be licensed into quarantine by the Local Trading Standards.
Pets that are not intended to be landed can be brought to the UK on board private boats. However they must inform the Port health Authority/Harbourmaster and these animals must at all times be restrained and kept securely confined within a totally enclosed part of the boat from which it cannot escape. If an animal is lost from a vessel in port, the Master of the vessel is required to report the loss to an Animal Health Inspector, the police or an officer of Customs and Excise.