Thanks Christine. Yes, I can confirm they are Chance and I do actually have two of the designs now. I was only aware of four in the original series, but had no other information apart from a mention in a trade magazine.
They were made in 1965, and probably had a very short production run - possibly no more than a year - so it is unusual to see five in one go. The two I already have are:
Prof. Charle’s Balloon 1783 ... (the one you do not have)
Vincent Lunardi’s Balloon 1785 ... (the one in the middle of your photo)
If I could trouble you for a close-up photo of the other four 'trays' (the correct Chance's name for them), this would help in getting the proper names noted and, with your permission, to use them for the next publication. Probably best to take the photos in daylight - if you have the 'tulip' icon on your camera, this will help with close-ups.