I wouldn't put too much faith into Checkatrade either. The guy I work for is on there and to be fair he's not a massive fan of it either. You can be the best out there, but if people don't fill in a review sheet you just slip down the list as people who have more recent feedback climb list when you search an area.
You could easily manipulate your rating on there too by getting friends and family to rate you high, all you need is a mobile number to 'verify' you left that feedback- plus you're not going to give a feedback sheet out if the job wasn't as smooth as it could of been, as the lower rating would cripple your average score- hence all the 9.9 ratings etc.