I can understand that, presumably aged 80, you feel uncertain as to where you stand. Obviously, as indirectly indicated above, if you have a UK passport as a British citizen (Nationality: British) then you can remain in the UK at will. If you do not then, even if you have older documentation saying you have Indefinite Leave to Remain, you cannot rely on that as the Home Office can/has been known to declare that "expired". Old_Geezer's advice to ask the authorities to confirm your status is sound because you presumably don't want to continue living with uncertainty.