"Collector Series" stamps?

Please pardon my ignorance on French stamps. My little grey cells are not flourishing in this period of isolation.

Looking through my accumulation of French stamps with a view to deciding on some thematic categories I looked at a few online sites and found a series of "stamps" with a YT reference of FR -COL and then a number.

I cannot find them in my Y&T stamps of France catalogue (unless I am looking in the wrong place of course?) so I wondered if someone with an idle moment might be able to enlighten me as to what these "Collectors Series" stamps are and where they might be listed? Are they Cinderellas or are they valid for postage etc?

Thought my ignorance might make someone smile!

The following reply has been passed to me by Richard Broadhurst.

You may have picked some of these up in the packet. They are issued by La Poste and are fully valid for postage generally "lettre verte" but can be other rates.

They started in 2008 and are issued alongside normal postage stamps. They are cheaper and quicker to produce, mainly having photographic images rather than being engraved and are principally targeted at tourists and non collectors as they have very attractive designs. They are listed in recent Yvert catalogues under "Collectors de la Poste" (2020 edition page 1352). Yvert stopped listing these in 2014 as there are literally hundreds of these (La Poste having sensed a very lucrative band-wagon!).

They are self adhesive and are sold on sheets with info about the issue, usually 4 or 10 to a sheet - see attached. The stamps are always in the same format with distinctive pseudo perforations. They are difficult to find used and are much sought after in this condition as they are mainly collected mint in tact. No catalogue price is given for them, but £1.50 is a reasonable price for a used example.

They are not listed or likely to be in the main catalogue listing as they are not really classed as normal stamps, they are in the same sort of envelope as our Post & Go series. I expect that La Poste sensing a gold mine will continue to issue these in quantity.

I hope this is helpful, if you need any further info please let me know.

Richard Broadhurst

This reply has been extremely helpful. The Y&T catalogue has many bits of information that I am only slowly starting to understand. It is very kind of Richard to explain it so clearly.