Finally got the TD6 ready to get back on the road, full clean inside and noticed a couple of areas where the cream headlining has come away/unstuck, exposing an orange foam (soundproofing?)

What is everyone using or recommending please to re-secure it?

Unfortunately, this is a common problem with all cars of a certain age. The cloth roof lining is backed by a foam which deteriorates with age and slowly crumbles into dust. Applying adhesive to the cloth will not work as it wont adhere to the failed foam and backing board. The only real cure is to remove the roof panel, peel off the cloth and scrape off the old foam and recover with new material.
I've seen on other car forums that the only temporary solution is to pin the cloth to the board using pearl head sewing pins or use one of the stud kits available on ebay https://www.ebay.co.uk/itm/133642061518_sk...BM9u7crb5l