Importing contacts from Windows Phone 10
After a few more failures where I tried exporting contacts as VCF and importing into my Google account (imported 9 out of 209 - no message to indicate why the remaining 200 didn't import) and trying to import the VCF direct onto the phone (failed completely with a message indicating the format was invalid) I eventually tried the Smart Switch app again, this time it prompted me to update it when I opened it so I did and this time it worked. It took a couple of hours but it seems to have worked ok.