The seller should complete the relevant section of the aircraft's Certificate of Registration, sign it, and return the Certificate to the CAA Aircraft Registration section.
If the Certificate of Registration is not available, use a Sale Notification Form.
Alternatively, a short letter or fax signed by the current registered owner(s) confirming the details of the transfer will be sufficient.
The completed certificate should be forwarded to the Aircraft Registration Section office rather than the purchaser in order to avoid delays in re-registration.