We always recommend that you send it via Royal Mail Special Delivery, as it is insured and traceable. This method is used in the jewellery trade throughout the UK.
We always suggest that you send the watch without the original box as this will cost more in postage. For all watches received with heavy boxes that you wish to be returned back to you with the watch will incur an additional £5 charge. Just be sure that the watch is wrapped securely in bubble wrap and a padded envelope. Please insert a note with your contact details and return address in the parcel.
NB: Royal Mail Special Delivery comes with £500 basic insurance. If you require more, just ask a member of the Post Office to increase it when posting.