Yes, to find a definite Yes/No is virtually impossible.
The UK Government (in a cowardly move) dumped the responsibility onto the individual Health Authorities.
So, you (or your friend) need to find out what the rules are in the Health Authority that he will need to go for for treatment.
This is an extract from a Gloucestershire Health Authority Document on the matter of patient payment..
7. There are three broad categories of overseas visitor exemption
b)
Those who are not part of the resident population
. Examples
are: UK state pensioners living overseas; some former UK residents
now working overseas; missionaries acting for UK-based mission;
armed forces members and crown servants serving overseas;
people visiting from EEA countries and Switzerland with
EHIC/E112/S2, plus people visiting from countries with which the UK
has a bilateral healthcare arrangement. A list of such countries can
be found in the guidance on the Department of Health website (see
below).
However the Government did bring in new guidelines for Health Authorities to help them decide if a person had 'ordinary residency' in the UK (& thus entitled to free health care) in April 2015.
The guidelines are here..
https://www.gov.uk/government/uploads/s ... ent-uk.pdf
Reading them it appears that it is still very much 'up in the air' & left to the Health Authority to decide. However it is important to note that
British citizens and their family members are exempt & that they are defined as
British citizens” have an automatic right of abode in the UK. A British citizen who has been living abroad, or who is migrating to the UK for the first time, can therefore pass the ordinary residence test upon taking up settled residence here. British Citizens who are no longer living and settled in the UK cannot be said to be Ordinarily Resident i
There is no 'time limit' set on what 'taking up settled residence' requires!!!!
So it is really back to the health authorities to set the rules..