I have just returned to this thread and would like to respond to those who have kindly made suggestions in answer to my question of 27 Feb.
Jalima and dbDB77 suggest that I apply for GB citizenship ( and yes, I would need to pass the English Language and general knowledge test) but there is a problem there.
durhamjen, you are right, I would probably need to stay out of the UK for 2 years to endanger my permanent resident status but that is not guaranteed.
May I just share with you a situation which others like me find themselves in, something that those who have only ever lived in the country of their birth could never envisage and thus may find hard to understand.
I was naturalised a US citizen but I was born elsewhere. My parents had to emigrate in the late 50s and, as a pre-school child, I, of course went with them. At that time, the US did not allow immigrants to retain the nationality of their birth. So they had to renounce their birthright in order to become US citizens and thus, I, too, renounced my birthright.
Several years later, I won a scholarship to study in Europe, met, married a Brit and remained in the UK. My only nationality was my naturalised one. When I investigated obtaining UK citizenship, I was told by the US that I would lose my US citizenship if I obtained a second naturalisation certificate. The US will not allow a citizen a second, obtained nationality.
Having spent my childhood and adolescence in the US, this was my identity and I found it difficult to give that identity up. In the 1990's, I was informed that the US rules had changed and that I could re-obtain the nationality of my birth without losing my US citizenship. This, I duly tried to do in order to be protected in Europe( I was born in one of the original EU countries).
But the country of my birth did not want me back because I had renounced my birthright( even though this was a prerequisite of American law at the time, since changed). I have appealed and have been told that I can get my birthright back if I live in that country for one full year, something I planned to do.
With Brexit, reobtaining my original citizenship will be of no use.......and so we go round in circles.
This is not a rant, just a true-life picture of what it means to be an immigrant.