Just undo the inlet manifold nuts, ease it back and fit the new gasket, less than an hour to do the job.

At least you can rule that out!

Perhaps putting a "skim" coat of RTV on the side of the gasket that fits into the groove on the intake manifold and another "skim" coat of RTV on the surface around the #1 & #4 ports? I think that would help prevent the gasket getting displaced when maneuvering it over the studs and also seal around #1 & #4 if there was any warping of the manifold.

Any recommendation for a brand for the gasket? Thanks.

Does anyone happen to know the torque settings for the manifold nuts?

Agree with the TLC. Mine's done 125k, so I check the basic stuff under the bonnet every couple of days, with a more thorough check if I'm driving any distance.

Get yourself a nice alloy inlet manifold, no more worries:cool:
https://i.imgur.com/b5tMBYcl.jpg

The torque and sequence re the plastic inlet manifold is shown here. Click

Interestingly it looks like the gasket is supplied in 4 pieces for at least some of the Chinese derivatives. The MG6 and Roewe 550 are both mentioned in the Aliexpress listing for the item shown below so I wonder if the 4-piece version is supplied/used at UK dealer networks:

https://ae01.alicdn.com/kf/HTB1KCg_j..._220x220xz.jpg

Great! Cheers - just what I needed. The one I ordered from Rimmers is a one piece, so it's interesting to see the separate ones on the Ali site.

Does the black uprated Viton gasket fail in time,or is it seen as a permanent fix?

The black Rimmer's ones will fail in time, but last longer imo. They're noticeably fatter than the green ones, so give me more confidence. See below:

https://i.imgur.com/y6LzYLg.jpg

Well I changed the IMG, but it's only resulted in a slight improvement. I've noticed that the cooling system seems to be getting very over-pressurised, so it must be the head gasket that's gone, and that caused the IMG to fail. Getting the HG done would cost more than the car is worth, so it looks like it's the end of the road. Shame, as I really like the car, old as it is.