DOORS:
Open and close the doors. Do the doors scrape and jump up as the latch hits the striker, or does it swing smoothly into place with a satisfactory “thunk”? Door sag can be caused by old age, worn hinges or simply a poorly-hung door. Some of the sag can be taken up by the hinge adjustment on the door. Look at the door gap, all around the door. It should be even front and rear, with no tight spots or huge gaps. Is the gap at the top of your Roadster door tight, both front and rear? That is evidence of a sagging car. Crawl back underneath and look for rot again. If the door is simply too far forward or rearward, that is easily adjusted. Look at the body line at the chrome strip where the waist curvature meets the fenders. Does the shape line up or does the door hang low at the rear? Do the door latches and locks all behave well? Do they simply need an adjustment, or are there other problems?
BOOT & BONNET:
The boot and bonnet are both simple sheet metal panels spot-welded onto an internal frame panel. They should not be full of rust. Boot lids can collect water at the lower edge, in between the two panels and bubble out. This is most common in GTs, where moisture can find entry past old window seals. The bonnet usually starts to rust at the rear edge and at the front edge, again in between to two panels where the spot welds catch moisture.
Do the panels fit the openings or are they crooked? Is it simple misalignment or is something not square? If not square, look for crash damage or previous bodywork. A little misalignment probably came from the factory. These were inexpensive sports cars, remember?
A common sort of physical damage often shows up on the boot lid. If the left and front edges stand proud above the body panel next to it, someone has tried to close the boot lid without releasing the prop. Look to the inside rib where the prop-rod mounts. Is it crumpled or cracked? This is evidence of someone abusing the boot lid repeatedly, not just once or twice by mistake. This is usually repairable, unless the rib is really torn and the outer skin is damaged as well. If the outer skin and support rib seem undamaged, the fit is easily remedied by simply pulling up on the lower right edge of the boot lid against the hinge stops to take the twist out of the entire lid. This is what I jokingly refer to as a "never-let-the-customer-see-this!" moment, as I fix the boot fit right before their eyes!
The bonnet usually does not get this type of damage, since it is harder to forget the prop rod. Damage to the bonnet usually appears as crumpling around the small raised section at the front, where the “MG” badge fits. This area is vulnerable to impact, and even a small “nudge” can push the grille badge against the bonnet. Have a look up underneath the leading edge of the bonnet, at the latch pin area. This section of panel should be flat, except where it is shaped to fit the outer panel. A big wave or wrinkle here means that the bonnet nose has been hit, and you should look for plastic filler above it on the outside.