The one I had was wonderful!!
I asked him a load of questions (well, a few) he answered them and explained things to me. Helped me with my paperwork and put me on the straight and narrow. I'd explained to him before the customer visit that I'd had difficulty in setting the boiler up correctly and this was part of the reason I'd chosen this particular customer as I didn't want to show him an especially easy one. (Then, at the customer's house, he told me how to interpret the readings on my FGA and explained why the readings on the boiler were within limits!)
He was also really polite to my customer and apologised to them both at the beginning and end of the visit and told them I'd passed and had done my job properly.
Then just before he went he asked to look in my van and was well impressed at how neat and tidy it was and said he'd have no hesitation in asking me to service his boiler.
His aim was to stop me worrying and to encourage me to phone him if I had a problem, as opposed to trying to create friction. His purpose was to get people to ask instead of covering up and, therefore, create better standards.
If he were to phone tomorrow and ask to see another, I'd have no worries - apart from the papework!