Judging by the MOT's, either he changed the mileage or his mate did. If it was his mate it would be interesting to know if he still is...'A Mate'.
My guess would be tha itwas 91K in 2009, by the time the 2010 MOT cam round it was 100K+ hence the decision to knock a few mile off.
It reports HPI clear, don't HPI do a mileage check ??
https://www.hpicheck.com/marlin/nmrHelp.do