Further to my final sentence/question, on googling around I found this ACAS arbitration scheme Q&A
Acas - Acas Arbitration Scheme Q&A
In a case of alleged unfair dismissal, what will the arbitrator award if they decide that the dismissal was unfair?
If the arbitrator finds that the dismissal was unfair,
they have the power to award reinstatement or re-engagement with or without compensation. If reinstatement or re-engagement are not sought by the former employee or are not considered appropriate by the arbitrator, they can award compensation.
See also -
Will we be allowed to choose the arbitrator appointed to hear the case?
No. However, if a party feels that there are exceptional circumstances which may affect the named arbitrator's ability to be impartial, for example if they have a connection with one of the parties, contact the Acas Arbitration Section immediately. Acas arbitrators are under a duty to disclose any actual or perceived conflict of interest, and will not be appointed to hear a case if a real conflict of interest is identified.