Work wants to replace me with younger person

Do not agree to attend this zoom meeting until you have sought advice, from a union if you have one, citizens' advice bureau or a solicitor. It would be worth the outlay in legal fees if you fear being made redundant.
When you agree to the meeting I am pretty sure you are allowed to take someone in with you, if only to take notes, if you do not have a formal representative. A friend took a journalist friend in with him, who took detailed notes all the way through, and it resulted in the charges against him being dropped and his being reinstated.

Charges of bullying from texts should have been addressed at the time, and if no complaint or action was taken at the time I do not believe they can be upheld. They may be attempting to discredit you by using them.
It is important to get the best possible advice you can and fight for your job; employers do try to get rid of older staff and replace them with younger, cheaper ones, and unless they have grounds for complaint against the quality of your work they are rarely in the right.
This whole process is deliberately designed to be as upsetting as possible and you should not attempt to fight it on your own. You are distanced from your place of work and somewhat isolated, and may be jumping to conclusions about nnew staff engaged.

I really recommend asking Citizens Advice.

I hope things go well for you.

Join a union!
Many years ago I received a letter from the hospital for operation that I'd waited a long time to have. I stayed behind at work to pull all my work in so that I wasn't leaving my workmates extra as my operation was scheduled for next next few days. All the work was completed and a handover done to my supervisor who agreed that all was ok. I had the surgery, was discharged from hospital and a couple of days later a letter arrived in the post telling me I was facing a disciplinary hearing for concealing incomplete work in my desk prior to my hospitalisation.
I cut my recovery period short and retuned to work to the most awful atmosphere! Although I really shouldn't have been at work I soldiered on and soon discovered that a temp who had been brought in just before I went off sick had decided she was having my job and she had engineered a campaign to discredit me! She had changed dates on incoming mail, secreted letters in my desk, made notes as my 'to do' list showing incomplete tasks and retrieved files from storage which she hid in my desk! What she failed to realise was the fact that I was in the union! The union rep wiped the floor with the temp and the Manager who quit within days!
The whole event made me so ill and although I was eventually exonerated it was a dreadful place to work after all!

^
Who would be involved in the Zoom meeting? Can you ask for someone impartial to be part of this - just as witness to whatever is said?
www.acas.org.uk/getting-legal-advice^

I second this advice. I worked at ACAS years ago. They will be able to advise you. Do not go into this alone and unprepared.

The HR dept belongs to your company and it is not on your side. They look for the best interest of their employer

I would talk to a lawyer that will advocate for you and your needs

I agree 100% with Katie59 if you are not a union member certainly take a witness with you and be assertive yourself do not be intiminated by any one.
You certainly can not be replaced they would have to pay the minimum redundancy of I think 22 yrs as set by the govenment

If you’re found to be a bully, then it doesn’t matter how good your work is.

Get advice and someone to represent you they cannot just replace you after 25 yrs without documented justification,
In practice if they believe you are going to fight you will get offered a settlement rather than go to a tribunal, because that will cost a lot and they may loose

Without sounding too unkind, your thinking you are good at your job, working unpaid overtime etc are not so relevant in this situation so try not to refer to them unless they become part of the discussion. Your company cannot take disciplinary action against you now for something that happened several years ago. Were you disciplined at the time and was it recorded anywhere? Even if it were, it is of limited relevance.
I have been in a similar situation so my advice, as already mentioned, is to have a witness and that you both take notes of all major points. If you don't know what is coming then don't try and defend yourself but insist that any accusations are put in writing to you (so that you have time to think about your reply) Word your reply very carefully and hand it to your manager. I feel this is better than just sending an e-mail. Also ensure that you know what the procedure is for dismissal so that you can quote this to your manager, i.e. do you have to have two written warnings before you are let go? but your manager should know this. Write down everything that you feel is relevant while you have worked there i.e. got any rewards or congratulations? You must be feeling very stressed and alone but please let us know if you need further help.

Make sure your supporter is assertive if you don't feel you can confront them.

Supporters aren't usually able to get too involved in meetings like this, unless they are official representatives such as union reps. They are there for moral support and as a witness to what is said.

Def have a supporter with you even if you're not in a Union. Tell them. you are recording the meeting, if not take notes. Make sure your supporter is assertive if you don't feel you can confront them.

I think the issue is that you’ve been accused of bullying rather than assuming someone is here to take your place. Although if you’re assuming someone from a BAME community is there through “positive discrimination” then I wonder what has come out of your correspondence.

Remember - someone has made a complaint, this isn’t coming out of nowhere.

You don't actually know that this person is a replacement for you and it's a big assumption to make. It sounds like you feel fragile though. Are you menopausal? That can mess up your thinking. It did mine for a while. If you think you are going to be criticised then look at how your actions could be interpreted. It's not enough to repeat that you are good at your job as most jobs involve communication with colleagues in some way. If this has seen to be an issue, then how can you resolve it?

Cross-posted, LMF - not ignoring you . Anyway, great minds think alike!

How did they 'find the texts'? Has someone accused you of bullying?

I think you are within your rights to ask to know who is going to be at the Zoom meeting, and what it is going to cover - you shouldn't go into something like that blind. As in writing (whether by email or letter), and copy in your union rep, who should be able to go with you to the meeting (virtually in this case).

If you aren't in a union (and everyone should be, unless they are willing to pay for an employment lawyer should the need arise), you can take a friend instead. They shouldn't speak, but can take notes of what is said and act as a witness for you. A union rep can intervene on your behalf, ask for clarification and so on, but at this stage will probably say very little, as they will be gathering information to use in any future meetings.

If there have been accusations against you, you should ask to know who made them and specifically what was said. Managers will sometimes say that this is confidential, but don't let them get away with a witch-hunt - you can't defend yourself unless you know what has been said and by whom.

How big is the company?
Does it have a proactive HR department? Importantly, do you trust them? Would they be part of the Zoom call the company want with you?
Are you in a Union (I'm guessing not, but worth putting out there).

There will be other advice coming at you from people, start making notes of what you think will be helpful.

Who would be involved in the Zoom meeting? Can you ask for someone impartial to be part of this - just as witness to whatever is said?
www.acas.org.uk/getting-legal-advice

I'm so sorry you are having to go through this. Can you tell I've been there too? I wish I'd asked one of my colleagues to sit in with me on a redundancy interview, the head of department or similar, because what happened was so unprofessional with the young HR woman completely blindsided by the Directors behaviour (he shouted at me and reached out to poke me - her hand grabbed him just in time. I think all three of us - including the Director, who was under a lot of stress in making a third of the staff redundant - were horrified. I've never told anyone about what happened in that meeting before).

Good luck.

Are you able to find those emails and any linked to them?

Several years ago my OH knew a man who was accused of sexual harassment and emails were produced to prove this. He was an IT person and was able to prove that the case against him was a put up job between the department head and a younger colleague. Both female. It went to an in house tribunal (It was the DSS) and he was able to prove that he hadn't send the emails and exonerated. Nevertheless, he lost his job and the two women kept theirs.

Sadly, it's not going to be a pleasant working environment for you. Try Citizens' Advice.

I was involved with Unions as a younger woman. The last one I was in was for the Civil Service. If you are in a union you could consider a tribunal if you are unfairly dismissed. It depends upon where and who you are employed by. If you are self employed or freelance you may be able to seek advice from Federation of Small Businesses. It really depends on your circumstances not sure if the CAB could advise you. I hope this helps.

Or are they just good at the job? Perhaps with up to date skills you don’t have? The idea that they hired a disabled person of colour just to fit a quota is pretty awful.

On what basis are you accused of bullying someone? You’re not exactly acquitting yourself well here so far.

BAME and disabled. I think that’s the correct interpretation not sure.

What do you mean by “fits the positive discrimination requirements”?