The paint was all new, the decorator bought everything new for the job (receipts provided). The apricot white was mixed at a reputable paint dealership. As mentioned, the paint manufacturer confirms there is a known problem of the gas like smell. I am obsessed with leaving windows open, much to my husband's annoyance at our large heating bills! Two thirds of the hous was painted, only a few rooms smell, but they are truly disgusting. One room had new wallpaper which was painted, others had been painted once before.
The paint company will be in touch with a solution, though they did say it means repainting all walls (he could have said with some sort of solution, I was too upset to take it all in after three weeks of upheaval).