Many thanks for the prompt reply. Do you know which towns and when they were issued - or where I may find this info. please? I have tried the SG website but it's not very forthcoming!
Try this site - it is in French but reasonably easy to go through - I've already applied the site filter for the sorts of stamps you're interested in. The site was created originally to specialise in the stamps of West France so I can't be sure that any of the collections shown are complete for the whole of France