Depends though doesn't it? If an engineer knows that it's a dodgy install ie non-commissioned appliance then doesn't he have a duty to cap it on that basis.
Yea but it might of been commissioned but the tenant has lost / binned the paper work, the only way you could have an idea is look at the install if it all looks correct and fga is fine
We don't live in a perfect world there has to be give and take
Same sinero someone moves into a house and they want you to check there boiler but have no paperwork as the last owners lost it / didn't leave it when they moved,