The Optare Solo seems to be part of the action tonight and we have it confirmed by a member of the PSV Cirle that it is former Halton Transport 59 LIG1677. It has been sold to a company in Berkshire reverting to its V247HEC registration
However, Reg's pictures from this evening show it is still not carrying a registration on the front of the vehicle, but the rear features a FN55ORJ plate. That shows on the internet as being the registration of a Vauxhall Astra police car which was being used for filming purposes.
My thanks to Reg for the information and photos