..... you 'cannot' issue a cert.
Nonsense! You still complete the Landlord's Gas Safety Record and hand it over. It isn't a pass/fail thing.
There are lots of misconceptions about various aspects of LGSR's. The first - they are not "Certificates". Corgi are guilty of generating a lot of mistakes, which of course get taken as gospel. The old Acops had mistakes too.
The whole thing about taking the closure plate (which most definitely IS A SAFETY COMPONENT!!!) off to "inspect the flue" is a bit daft. Even with a torch you don't get to see much flue. You can look for debris at the bottom of the "builder's opening", but as long as the aperture in the bottom of the CP is well clear, it doesn't affect the operation of the fire at all.
It seems daft to me that Landlords' appliances do not get serviced annually. It's in the gas Safety regs just as a LGSR is.
There are some real bits of nonsense about fires. One suggests that they do not need to be fixed to the wall. A fire is not a free standing appliance - it has a rigid pipe not a flexy hose. The Manufacturers Instructions did not always say that the fire had to be fixed to the wall, but they sure as hell didn't say that it shouldn't be. Appliances have always had to be "secure". Nontheless, most oldies are screw free.
A current topic on Gas-news is about fires which belong to the tenant. It has been assumed for some time that, as part of a LGSR, the fire had to come off the wall so the flue could be inspected. I checked the regulations, and it doesn't say that. If the flue is faulty the landlord has to fix it, (assuming he has given permission for a tenant's own fire to be used) but he doesn't have to test all his flues every year in case someone wants to put a fire in.
If a tenant puts a fire in, it must be serviced in accordance.... every year, The flue would be inspected then. No need to do it twice in a year.