Having read through this thread a couple of times I think it is perfectly possible that people may be confusing what kind of notice might have been issued in the first place.
I can fully understand non-railway people automatically thinking Penalty Fare Notice (PFN), or Report for Prosecution because that is what they see and hear on a regular basis on here via either a Travel Irregularity Report (TIR) written by railway staff or, following a Witness Statement which will have been compiled after an interview under caution conducted by a PACE (Police & Criminal Evidence Act 1984) trained inspector. As 30907 says, if you are being questioned, that amounts to an interview and whilst limited in its scope, a single question can be considered to be 'an interview'..
The Railways (Penalty Fares) Regulations 2018 apply only to PFNs.
Given the confusion around the sum of £24.90 referred to, if and it is only an if, but if that is the correct fare for the journey being made it is perfectly possible that a UFN was issued. That is an Unpaid Fare Notice and is issued on a pad form that looks a bit like a PFN, but is not issued subject to the Penalty Fares Regulations. It is simply an invoice for the fare for the journey to be paid within 21 days of travel.
I had 40 years in railway revenue protection and the last 20 years running prosecutions. I can say for certainty that if this UFN remained unpaid, prosecution would not be statute barred as suggested by 221129. The TOC would have up to 6 months from date of commission of the alleged offence to lay an information before a Court and they have clearly done that.
Just to touch on the matter of seeking proof of identity at the time of a report, rail staff will ask for confirmation of the details they are being given and in most cases something will be shown that satisfies the request, but it must be remembered that we do have generally good civil liberties in this country. If someone is asked to show their identity and says 'I haven't got anything', but a call by the questioner to the helpline confirms the name given at the address given, rail staff will have to accept it as correct. On the subject of BWV or CCTV, if any existed, footage is usually only generally available for 30 days from the date of any incident and as Stigy says, unless there was a very compelling reason to mark it proactively to be retained, footage is very unlikely to exist now.
On the understanding that this does not involve the OP, this has to be challenged and I suggest that the OP may wish to put together any supporting information to confirm where he was at the time. To save much repetition, the OP might wish to go back to post #5 by Neutron for ideas here.
Along with the letter the OP should include a recent head and shoulders photograph of himself, with his name in capitals and signed with his normal signature on the back and write to the prosecutor enclosing copies, stating that he has been the victim of identity theft and invite the prosecution to withdraw their summons.
If it were me, I would send a copy of that letter and the supporting photo etc. to the Legal Advisor at the Court where the case is to be heard as soon as possible and a letter explaining your dispute.
You should also keep a copy of everything sent for your own record and await a response.