I know little about CENTRE accreditation so am unaware of what checks are made on the facility or its employees
There are many checks on vehicles, documentation, procedures, published syllabus, facilities including correctly marked reversing area - the list goes on and on. All trainers employed by the centre have to be on the DSA LGV Instructor Register. This makes recruitment interesting as they are thin on the ground!
It is NOT a tick box exercise. Otherwise many other trainers would have gone for it.
Pete 
Endgame:
Peter Smythe:
Hope this “trainer” never hopes to work with us - I’d give him 2 days before he was down the road looking for work. We have a strict “no shouting” policy and always have had. No professional trainer should be abusive at any time let alone shout.
Pete
I know the trainers. There is 3 of them. The owner is hot headed and clearly ready for retirement. His son is spot on and the weekend bloke is also spot on. If you’re unfortunate enough to have the owner, Steve, then you have to brave yourself to be shouted at if you don’t grasp things straight away! Perhaps being shouted at works for some people? Who knows. With me though, it just made me more nervous! That’s why I ended up going with chevron instead.
I had an instructor who would constantly shout at me for getting things wrong. When I failed he gave me a grilling on the way back to the yard. I had a retest prepaid through a broker (yes I know, that was a stupid idea) but I couldn’t face going back there. Paid another £1000 out of my own pocket, went with Peter Smythe and passed first time.