MX5s suffer from rust in areas that cause MOT failures.
Mk2 and Mk2.5 suffer rust attacks to the rear of the sill and wheel arches areas.
It usually shows on the outer sill and the wheelarch, the bit you can see.
Depending on the extent of the rust, an MX5 may only need the outer sill repaired.
This Mk2 car had very poor outer sills but the inner sills and box section were in very good condition. Here we have painted the re-inforcement panel, prior to the outer sill being replaced.
Once the metal is cut back to remove all of the rust, a new outer panel can be welded back.
There is the finished sill.
Obviously, not all MK2 / MK2.5 only have outer sill problems. But if you catch it early, then you'll avoid further expense later!