When the ill Brit expat gets to the UK and perhaps takes up residence with a family member and then reports to the GP doctor with whom he never cancelled his registration he would get treatment in the NHS system, perhaps saying “I’ve been on holiday I Thailand for a month and became ill whilst there “. Health tourism is a problem for the NHS. Examples are Jamaican pregnant ladies flying in to have their babies free of charge and Asian heritage Brits bringing over their relatives from Pakistan for treatment.