Other EU countries have regulations in place regarding residency and insist that anyone living there has access to medical insurance, either private or public, or is paying in to the system. The UK has no such system and provides free healthcare to anyone who declares themselves resident. One NHS chief even said that people entering the country would be entitled to free NHS services from day one of arrival simply by giving a relative or a friend's address.
Yes, I should imagine the S1 system works both ways but, when working as a nurse, anyone attending the surgery with an address in the area was given the forms to fill in and generally received an NHS number within a week or two. The same with what was the E111 and now the EHIC. No guidance was ever given from the local trust regarding claiming for this system and people attending were simply given a temporary resident form to fill in, the same as for someone visiting from, say, Bolton or Glasgow would get. Pensioners from any country living in the UK were automatically registered and I doubt if any of those working in the surgeries or the local trust would have any idea what an S1 form was.
Spain, for example, does have the systems in place for claiming the money back from the patient's home country. Even if you turn up to the A&E without an EHIC they will telephone Newcastle to get your entitlement faxed through and claim that way.
If UK leaves the EU, how will that change? Unless more robust systems are put in place and GP surgeries start employing people to chase up the money then nothing will happen. Until a system of registering anyone from abroad is brought in (and they don't even know how many are in the country because there is no register of foreign nationals residing in the UK) then it will be impossible to keep a tab on them.
We even had people who had moved back to their country, whether it be India, the Caribbean or elsewhere, who remained registered and a friend or family would come in and collect their prescription to post abroad. Evidence for this was difficult to come by but it was playing the system currently in use in UK.
And that former health minister is talking through her ......well, she is. There is no such thing as NHS UK and only those in England pay for their prescriptions. Every other area gets them free.
This is yet another case of blaming the EU for the UK failings.