Steve, can you go over the whole set and see if there's any registration number moulded in anywhere? Use your fingers and feel for it rather than look to start with as they are sometimes very hard to see but can usually be felt. If we can find one piece with an RD no we may be able to track down who made them.
BTW I've seen a different set on the same tray (two examples in different colours in fact), also unattributed and not seen in any of the catalogues I've looked at so far. Using the same tray for more than one set isn't unknown - if it was just one other set seen then it could be two part sets joined but I can't believe both the other sets I've seen were marriages. The tray fits better with your set set though!
