The problem with the Fiesta Glass (Ltd) range is that it did evolve quite quickly, from one pattern to another. Successful patterns might have carried on for several years, others could be dropped quite quickly. It must also be appreciated, that all of the later patterns were transfer-printed, and generically produced for many other companies.
All the exclusive patterns solely designed and developed by Chance; Swirl, Calypto, Green Leaves, Night Sky, Psychedelic, CarrĂ©, etc. - ones that are predominantly collectable - were stopped from the mid-1970s. Sights of London, Series 2 (c.1976, assuming that this range was commissioned by Chance) was probably the last, and still being produced with Fiesta labels, so post-1981. That is not so surprising, as Fiesta Glass inherited a great number of transfers and were merely using up existing stock.
Chance Expressions was also intended to cover the glass made by Chance Brothers, but it would have been remiss not to have a passing nod to it's legacy: Fiesta Glass and Joseph Joseph. But it was never intended to cover those subject matters in great detail: I'll leave someone else to write that particular sequel in 2020 when it's all approaching 'vintage' status :24:
Conclusion: Anything produced by Fiesta could be scarce, but I doubt that makes it any more collectable, to be honest.