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Yes, Baz, I think once Buenchico (who gives excellent advice on AB on a wide range of things) recommended using a council testing facility because, as you say, there's nothing in it for them to 'invent' things that don't really need doing. Unfortunately, there are none of these near where I live, but the local village garage seems pretty good. For the last test, all that was needed was new wiper blades, which they got, fitted and when I went back (after the inevitable pacing around) said it had passed.
So much better than other places I've used who failed the car on something small like a numberplate lamp or brakelight, tell you it's failed and ask if you want them to fit a new one!