Usual Rot Points

[E_T_V]

200/400 wedge
Where front/rear end of bumpers rub on front/rear wings
Lower front of rear wheel arches where it meets the sill

Maestro/Montego
Rear wheelarches
Door bottom corners
Rear panel behind the bumper

200/25 bubble
Door bottoms
Tailgate hinge area
Rear wheelarches

400/45
Rear wheelarches

600
Rear wheelarch where it meets the bumper - Later 600's have a modified bumper design to reduce the rot trap

800
??

[nicko500s]

i used to laugh at my mate cleaning inside the lip of his rover arches but when the front arches bubbled up on my other car i started to clean the build up of mud out of mine as well and so far no corrosion

other rot points on th 45 are the outer corners of the front footwells by the bungs.