What lurks beneath!

X Reg 20VT six speed in Moondust silver.
The engine fired up on the first turn - great sounds from those five cylinders.
Pulled it out into the open and those lines are still stunning especially in the golden light of evening.
The job on hand: sand off some rust from the wheel arches.
Good news it looks worse than it is. Most of the rust drills off to leave shiny metal underneath hooray.

Paint some Hammerite on the bare metal as a botch ahead of getting it done properly at some stage (along with the belts etc and replacing the heater matrix which some forum friends help diagnosed was leaking).

Everything works. Not bad after being dry stored for six years or so.

Then I look underneath. Quite shocked actually for a car to look so smart in the cabin and around the bodywork, that the underneath is so darn ugly with corrosion. Crispy coil springs. Surface rust everywhere. I’m not technical but the rails that run parallel to the sills (chassis rails?) have layers coming off. Bits of floor pan coming away. Its a bit of head scratcher as to how bad its got. I’d welcome observations on how much work is involved in simply getting an MOT?

Pics attached.

Rear suspension tower from below; jack hole at the back; floor pan where I peeled away a bit and exterior (obvs)

Rear beam can be swapped over - I just refurbed a spare for one of my projects.
Get the filter cover off that osr jacking point and have a good poke around.
Keep getting the underseal off to see what its hiding.

Check front inner wings/chassis rails behind liners near where the subframe mountings are. Get boot floor carpets out and check where boot floor meets inner wheelarch - if any signs at all get the seam sealer out of the joint and havea good poke around, be prepared for it to escalate.

Most of it is fixable and not too difficult for someone competent.

That’s encouraging thanks. I did have a look under the boot carpet and thankfully its all pretty clean under there. Also checked the fuel tank restraining straps. They have surface rust but still look strong enough. I’ll crack on with removing some more under seal. Funny I thought that was a layer of metal initially but I see the floor pan underneath (above really) is metal.

Those pics look encouraging

I think the basics were covered above, but to reiterate, I'd lift the boot carpet and look carefully around the edges. Very common to rot there. Take the rear quarter cards out and look in the cavity above the sill. The badge pins can let water in. The last place (from experience) is behind the front strut. You'll need to check the seam sealer is all in good order. Of course being an older car you may still get a surprise.

As a matter of interest, what counts as terminal corrosion as far as the Coupe is concerned?

When your pockets run out of money I don't think I've ever seen one that couldn't be fixed, but it all boils down to cost

Yes I can vouch for that....

The 'worst' places that I can think of are as szkom reiterated, the inner wing area near chassis rail/subframe mounting, and the rear of the sills - which when its going pear shape escalates dramatically - as he said (and I forgot to), take rear trim panels out (speaker area), take a deep breath, and pray. I am very lucky that three of the four coupe's here are spot-on in both areas, not checked the fourth one (yet) as its a daily driver.

Me also, I've spent a significant amount of wedge on my sprinty getting rid of the dreaded tin worm.

I get it so the BIG REVEAL will be taking the rear trim panels off. Fingers crossed. Is that screwdriver leverage and some pop plugs?

Rear bench, front seat belts, and some trim. Not the hardest job, but you do want to be careful pulling the rear cards about as they can split

Yes, as above - when you're ready to take the card off (don't miss the small black phillips screw at the very bottom), pull off the vertical part of the door seal then introduce your jemmy at the B pillar edge gradually to release the plastic poppers that secure the cards.

Thanks guys 👍

At the front, take your plastic inner wheel arch liners out and have a good poke around. I've just finished doing a fair bit of welding around there including a hole in the passenger side inner arch that I could put my fist through! All repairable, just time consuming.

I had one of those!

Yep that's the one! Bad design... the plastic liner rubs against the inner arch, mine has a sunroof and the drainage pipe is directly above keeping it nice and wet