There were no signs of burnt fabric.
Bamber pulled up Neville's pyjama top. He didn't want the burn marks to become an issue as he knew Sheila in a rage would not be calculated enough to do this.
I would have thought, given that it was his neck area which was burned, it would have been far easier to have pulled the pyjama top down from the neck-line rather than up from the waist. In fact I can't imagine, as he was wearing the top, which wouldn't have been other than fitted, that it would have gone up far enough, the arm pits restricting further movement, to allow for burning skin without burning material.