One step forward... four steps back

This is a section of wall in our boxroom. Today I was supposed to be just freshening it up with a quick coat of paint. Trouble was, when painted, the lining paper started to come away from the wall and ceiling in several places. In the end I took most of the paper off, leaving bare plaster than needed some holes and cracks filled in (now done, and drying), then sized (wonder if that was even done before explaining the falling paper), wallpapered and finally painted again. Sigh.