Just painted a bathroom in old cottage, paint is Dulux Matt emulsion, new tin.
It has left a chemical to stale smell, could this be a reaction to the old surface which was previously papered. Walls were stripped, filled and sanded
Yes this could be a reaction, most likely to old paste residue on the wall. Contact Dulux customer care team and report the issue, most likely they will tell you they have never had this problem anywhere else. These can happen in particular when manufactureres change formulas which they frequently do. Crown had a major problem with this around 6-7 ago on their breatheasy range and more recently Valspar when they changed the formula. A solution for you, though costly would be to re prepair the walls and put 1-2 coats of Zinsser BIN primer (or alkali resisting primer) This will seal the smell, then repaint in chosen colour and brand emulsion. Hope this helps.