mjt

We all know Fords have always been crap for corrosion, but no where near as bad as Rover and British Leyland. 

That's a bit of a generalisation. You're dead right about British Leyland, of course, and the Rover 100 got it's legacy from them, but I used to own a 75. It was a petrol 2.0L V6 so didn't suffer from the dreaded K-series head gasket issue. It was 10 years old when I sold it and there wasn't a spot on it. It had other design and build quality issues but the bodyshell protection and paint finish on those models, certainly the earlier ones, was spot-on. There are also quite a few 10-year-old 25's around that are still looking good. My wife had one for a while and it was also spotless.

As for Fords, my Mk1.5 is 10 years old and still holding up well. As I said all these old cars were produced at a time when the manufacturers were taking body protection seriously.

It needs both to be done adequately for proper protection. Paint won't protect well on it's own because there's always the problem of uneven coverage, especially on edges and corners, and pinholes and galvanising will corrode in the presence of road salt if unprotected by paint. Cavities also need to be well wax-injected to protect from condensation.

I suspect we've passed the high point of manufacturers applying good protection to bodyshells, around the turn of the century, and they're now starting to compete to shave the costs of providing it.

Hey all, started having problems with the central locking on my mk1 focus, if the passenger side door is unlocked the drivers side won't lock using the remote it just locks and then bounces back open (Doesn't even appear to try lock the passenger side) yet if the passenger side is already locked then it locks fine

The most obvious cause would seem to be that you've lost the drive to the lock motor on the passenger door. Maybe a corroded connector, a fracture in the cable where it passes into the door or worst case the motor itself. If the passenger door is detected unlocked the system will bounce the other locks as you've described.

I'd try changing the relay first. Just because it's clicking doesn't mean it's ok. The click comes from the armature but a contact could have failed. You could try swapping the relays for front and rear as a test to avoid shelling out on a new one unnecessarily.

Has anyone checked your driveshafts? Just wondering if one is bent. It wouldn't take much misalignment to cause a vibration.