the import probably crashed a couple of weeks ago. outlook is good at freezing up, especially if it has issues with the PST file it is reading. I suggest you try again.

Thank you - this was the second of two attempts, looking now the folders "outlook import" and "outlook import 1" appear identical (having got no further than a few deleted items from some time ago), suggesting either that the second import did nothing (if cumulative) or both for some reason got to exactly the same stage. Looking again, though, the deleted folder contains a lot of emails from 4 days in 2020 which I can find neither in my Outlook deleted items (which mostly doesn't go back that far, apart from 1 item that hasn't transferred) not in my Outlook inbox. (Nor for that matter in webmail). So something very odd seems to be happening.

PS Around that time in 2020 I bought a new laptop and had to import the old pst file to Outlook, so it seems possible that it's found that old file somewhere. But if so I don't know where.

I will give it another go. Two questions if I may - firstly, does it make any difference whether Outlook is open or closed during the process? Secondly, do you have a rough idea of how long it should take, as there seems to be no way of telling whether the process or frozen or proceeding very slowly?