i bought mine a few months ago on 49k and it had history but no mention of the belt, so i booked it into A P Developments by me, for cambelt / tensioners / aux belt.
i bought the gates kit (as is best for 172 apparently)
went to garage and about 5 hours later, he showed me the old belt and ...... it was a gates one (not renault) so it had been done!
But still, I dont when it was done, so peace of mind. at least you KNOW its done.