the mother from hell

Tell her that you have given the clothes airer to some one else "who needs it more than me. It is time I bought a new one, anyway. I have been using that one for too long"

Men friends? How old does she think you are? Fourteen? Bring home a really dishy one (even just for a cuppa, or to read the meter for you) and then tease her about being envious.

Just remind her that you are not a child any more.

...unless it is dementia of course.

Have the following conversation "I love you dearly but there is something I need to say to you ..." and then tell her. Give her back her clothes airer saying "Thanks, it has given me brilliant service but I want a new one".

I know it may be easier said than done, but what you describe is enough to make anyone's life miserable and it can't carry on. Sneaking a man friend out with a blanket over his head, I'm impressed that he played along, he must really like you Silverfish. .

Silverfish Can you not suggest she goes to meet ladies of a similar age during the day do you have a Age UK group near you where she could maybe spend a couple of hours and take the onus off you for a while,does sound as if there is an up and coming personality problem or has she always been like this.On a funny side you could always change your car and not tell her or change your hours of work but seriously I can imagine it is getting you down somewhat as you should be able to lead your own life without the constant interuption from your mum.

Does she see other friends/family or are you her only contact? She sounds very lonely and as if she has nothing else in her life

Yes if she has had a radical personality change absent may be right.
Alternatively she may just hate being in her 80s and resent you for your youth - people do sometimes take things out on their nearest and dearest, or someone that will put up with them being bad tempered and demanding.
But why are you taking so much notice ? Why do you pick up the phone? Or stay in the room when she starts lecturing you? Is she like this with other people or just you?

Sounds like dementia setting in.