On the 1st January 1973, the United Kingdom joined the European Union. It was not until the 1988 Immigration Act that the implications of free movement were defined in statute.
Under Section 7 of the 1988 Immigration Act, those who are exercising EU Rights do not require permission to enter the United Kingdom. ( See text below.)
Prior to 1988 the Home Office practice was to grant Leave to Remain under the then Immigration Rules pursuant to paragraph 140 of HC 169. A Residence Permit granting a period of Leave to Remain for five years, would lead to a grant of Indefinite Leave to Remain after four years residence . ( Paragraph 144 of HC 169.)
Those EU Nationals who have been resident in the United Kingdom for a period of thirty four years or more, may have been granted Indefinite Leave to Remain and as such need not apply for the new settled status, as they have settled status already.
The challenge they may face would be in proving this entitlement following any departure and return to the United Kingdom following BREXIT.
A number of people who fall in this category may never have applied for naturalisation, either because of a prohibition on dual nationality , or because the enactment of Section 7 of the 1988 Immigration Act rendered such an application unnecessary. They should consider making an application for Naturalisation now.
Section 7 of the 1988 Immigration Act reads: