These were intended for use on the junior gaspipe market in the 80s... Peugeot for example supplied these in the UK along with some gawd awful 'sticker' finished junior racers, atb's, girlie bikes whatever... They were also sold for aftermarket fitment by at least one wholesaler I know of. One spec level down (at least) from the Simplex / Huret / Falcon / Raleigh etc. etc. 'Eco' derailleur. I'd guess only collectible to the person/s looking to have a complete Simplex production set.
Bob Reid
Stonehaven
Scotland