Thanks for the suggestions as to editing the theme. Getting things back to where they should be will take some time as I’ve made a load of changes; for another day, but obviously (now) vital.
@ernest
I didn’t have a .post in style.css so have created one and set the background to white. This sort of works but the background white is hard up against the text boundaries top and sides (but not bottom). Do I have to create some type of border/margin to correct this?
David