Update from the NHS for U.K. state pensioners holders of the S1 who are not covered under the withdrawal agreement. 
“Can S1 certificate holders access healthcare whilst visiting the UK?
If you have a UK issued S1 which you’ve registered in the Member State you’re now living in and are visiting the UK, from 1 January 2024 you can get free NHS treatment in England.
Any S1 holder wanting to access NHS treatment in Scotland, Wales, or Northern Ireland must check with the relevant NHS authority.
If you’re asked to show evidence when accessing treatment in the UK, you can show either:
your UK issued and registered S1 certificate
verification you were issued an S1 from us
NHS charges must be paid where they apply to ordinary UK residents, such as prescription charges in England.
Accident and Emergency services and services that are deemed urgent or immediately necessary will always be provided free at the point of delivery first in the UK, with entitlement to NHS care determined afterwards.
UK issued S1 holders seeking pre-planned treatment in England, must make arrangements for that treatment with relevant providers in England. This may include any waiting period, assessments, or referral processes which may apply, and sharing of any medical information to help ensure continuity of care”.
Due to the NHS changes in charging regulations which came into force in April 2015 will mean that UK State pensioners who live in the EU or elsewhere in the EEA will now have the same rights to NHS care as people who live in the UK. This applies to all pensioners who receive a UK State retirement pension and registered for healthcare in Europe with an S1 form. *This now only relates to pre transition period pensioners. There are exemptions.
Others should use the EHIC or have private insurance.
Also exempted from charges:
There are several groups of people who are exempt from charging, or entitled to free care because they remain ordinarily resident here despite spending time outside the UK. UK Crown servants, British Council or Commonwealth War Graves staff, those working in UK government-funded posts overseas, and the spouse/civil partner and children under 18 of these people, are exempt from charging if they were ordinarily resident prior to leaving the UK for that purpose. Those who were not ordinarily resident in the UK before taking up such a post will be charged.
There is also no change for armed forces members, war pensioners and armed forces compensation scheme recipients and their families, who are not required to have formerly been an ordinary resident of the UK
State pensioner no longer to be in possession of a EHIC when visiting your home country but should provide the UK with their S1.
First posted in March 2015. Lost due to server crash.