British Domestic law provides that a transferring ‘life’ sentence must have a ‘tariff’ attached on return, whereas those on a determinate sentence cannot have their sentences re-examined and must serve the full sentence handed down by the Thai courts.
A simple solution to this problem without any need for altering the treaty or introducing new legislation, I suggested to Ms. Thompson, would be to follow the Australian and New Zealand examples whereby their governments offer full support as a matter of policy to their own citizens imprisoned in Thailand, once an individual had served an equivalent sentence term to what they would have received if they had been convicted of a similar offence in their home country.
British Transfer Treaty with Thailand ‘deeply flawed’ say British prisoners in Bang Kwang – insidetime & insideinformation