https://mot-history.net/
Just came across this on a UK site, Will be of interest to a few on here with UK cars.
Provides MOT history from 2006 on, With fails, advisories and more importantly mileage! (Although mileage is only 2011 on)
Best of all it's free!!
Have ran a few reg numbers, Gives very good detail from suspension/tyre advisors to fails (Emissions, Light focus etc..)
Now if only our lot here could do something similar for NCT.