This is from LittleGun:
It was taken again a few years ago by a Netherlander who apparently transferred the company to the Netherlands (the end of 1980, the author still had a telephone contact with the company in Liege, concerning a Martini-Francotte rifle in 22, in the vain hope to know the date of manufacture of it: the files were not already consultable any more...).
To the best of my knowledge, even the building in Liege is gone.
Here is the last contact info for Derksen that I can find:
Auguste Francotte & Cie
Rue du Trois Juin, 109
Herstal
Fax: 011-32-42-40-46
Francotte@cybernet.be
The email, address and fax are Belgian.
Pete