Welcome to the postcard.co.uk board, for discussion on all aspects of the hobby. You'll need to register to post but this only takes a few seconds and gives you access to more of the features and options available. Please read the the HOW to REGISTER article first. thanks
I have what appear to be 7 x Valentine's proofs or reference cards as they carry the same number as on the finished colour postcards produced by Valentine's. These are in black and white and are plain backed cards. I have been in contact with a Bonzo website and Richard who runs that site also thinks its likely they could be some sort of Valentine's reference or proof card.
I am a bit out of my depth with pricing on these things - they are a bit out of my comfort zone! So before I put them in my postcard shop where I would probably end up setting the price either too high or too low I wouldn't mind any input.