UK - Probation and extensions [duplicate]

Is it possible for a manger to extend a probation (almost indefinitely) without HR being involved?

I believe that my manger has been lying to me about my probationary status for quite some time, to what end, I do not know.

I started in June and handed in resignation last week.

In July it was extended by 1 month due to travel constraints - this letter is on file with HR stating that the probation ended on 1st October.
I also received a copy of this letter.

Around the first, for arguments sake we'll say it was the 2nd, I had a 121(mostly meeting to discuss targets, process and anything else really - mine were mainly me walking on eggshells trying to improve my chances of existing the probation period) with manager, he congratulated me on passing probation. I then told him of an incident that had occurred (in another post).

Since then I've been told by him that my probation is ongoing, it started out with a 2 month extension, then it went to December and then finally the end of January. No real reasons, just 'it is' - I've received no letters, no HR contact, just verbal via manager.

HR have no record of these extensions.

So, is this a thing? Is it allowed, does it stand - did he over extend his rights as a manager? Is this even allowed to happen?

Apologies for the number of questions - hopeful that someone may have an answer or two.

This continued probation was a contributing factor to my eventual resignation.

many thanks!