Thanks rjo. The only damage to my passport is a small tear (about 12 mm) at the edge of an internal page and to be fair it hasn’t been queried on passing through immigration anywhere including the UK, but of course one is advised to get a passport with any damage replaced because some countries’ immigration officers can get agitated about the slightest problem. There isn’t any damage to the key pages with my picture which is what would cause problems with a UK renewal application (perhaps that’s the case with yours?) and other very specific damage (see below). Mine is otherwise only going through a standard renewal and that’s all I applied for, though I pointed out with a post-it note that one page had a small tear in it.
The UK Passport Office’s definition of damage (which then crucially requires identity to be confirmed) is:
details are indecipherable
the laminate has lifted enough to allow the possibility of photo substitution
discolouration to the bio-data page
chemical or ink spillage on any page
missing or detached pages
the chip or antenna shows through the end paper on the back cover for the new style e-passports
the chip has been identified as damaged after investigation
None of those apply to mine.