Can my hr dept make me prove the terms of my employment?

[Lirogiro]

My work is currently going through a restructuring process, the second in two years.
I was originally employed on a fixed term contract, but following the first restructure a couple of years ago i was moved onto a permanent contract.
Now the second restructure is underway and the hr dept say that they have no record of my permanent contract (hr was regionalised in the first restructure, so all the staff are different and records were moved to different locations).
I'm on maternity leave and have been asked to send proof of my contract by monday (so within one working day) or i'll be considered as in a fixed term contract for the new restructure and not able to apply for any new jobs and much further down the process for being allocated a job ie much more likely to be made redundant.
I can't find the spatchcocking permanent contract, so can't prove that my contract type changed, but can they do this to me? It seems ridiculously unfair!
Any hr knowledge would be gratefully received, thanks!

Did anything else change at the same time (ie additional benefits, pay rise/cut, different hours)? That could be used as evidence to show that T&Cs changed, implying a contact re-write even if you can't find the written records.

It does see unfair. When did your fixed term contract end? Were there policies/procedures in place during restructuring which you can refer to which resulted in a permanent contract? What usually happens at the end of a fixed term contract?

There was no change to pay or terms and conditions although my work location changes, but that wouldn't be related to contract type. Annoyingly i went on maternity leave the month the original fixed term contract ended and what they do in that situation is extend the contract to cover the period of mat leave, so i can't even say they were continuing to pay me after the original fixed term contract ended.

How long have you been employed there?

No great expert, but I would put them on notice that their request is unreasonable in terms of the timing and unprofessional. Put them on notice to provide evidence of the search they have carried out within their various regional offices. Remind them of their obligations under the data protection act to safeguard your sensitive personal data.
If someone more expert on here can confirm, i think that switching your contract terms so significantly would amount to actionable constructive dismissal, fact your on maternity leave may add a sex discrim aspect.
Remind them that contracts do not need to be evidenced in writing to be valid - if you have any emails or letters about your permanent contract, wave them in support of the existence of a permanent contract.
I despair that people this incompetent are put in charge of people's livelihoods.

Flowery will correct me if I'm mis remembering, but I believe less favourable treatment of fixed term workers is now not allowed. What they are proposing sounds very much like discrimination on the grounds of fixed term worker status.

This should now be irrelevant, but if their records say fixed term and you can't prove otherwise then their records will stand.

Yes hermione OP can't be treated less favourably anyway, which would mean equal access to internal vacancies etc

OP if you've been employed 4 years you are permanent anyway so won't need to prove anything.

How are they claiming you are fixed term anyway if they have no end date for you? If there's no date the term isn't fixed