Nigel,
Have you tried to trace the current whereabouts of the vehicle shown in the post above. A Google search for the firm P O Baker & Sons throws up a garage in Station Road, Gillingham, Dorset, SP8 4QA. Using Google Earth to go to the address, this is what you will find:

I have highlighted the sign to draw attention to the date on it. That may, or may not, be coincidental, but I think the entrance to the larger building behind the white one looks very similar to that in the photo.
DVLA shows no record for the registration FX 33. It might be worth a quick phone call to the garage to enquire?
John