Towards the start of this year, we had to fire someone I was managing due to (among other things) poor performance. We/I offered to supply a reference for ongoing employment. Their new company (I understand they've signed a contract already, for a somewhat related role) has now reached out for one, and addition to the usual questions about confirming employment dates they also have a bunch of questions about rating candidate performance, would I hire them again, etc. I gather from the form that these are standard questions for their process but I don’t think either me or the former employee were expecting it.
Constraints:
I don’t want to lie
I don't want to be mean to the former employee, while I don't think they were very good I have no animosity towards them
I don't think I can easily dodge this since last week they reached out to confirm that I was still OK to do this (obviously this was before I saw the form the new employer would send)
It's hard to write something generic because the employer's form is not free text but rather has specific questions as outlined above
I obviously don't want to do anything that could get my company (or me, I guess) into legal trouble - this is UK if that's relevant.
I have already asked my manager for advice and also written to our HR, plus asked friends/family who are not involved in the situation. I've yet to hear back from HR but a common suggestion has been to write to the former employee and confirm:
What they said about their departure from our company to the new employer, so as not to cause any problems.
Given the above constraints, whether they still want me to provide a reference (although if I don't I'm not sure what the new employer would make of it).
What would be the best course of action here?