First the bad news...
Stripe is wrong colour in the photos but could just be the camera. Its an RS2000 stripe by the way.
OK then..Some Mexicos where banged as 1600GT, On engine it always read 1600GT regardless of outside badging . It looks like a type 49 shell which indicates Mexico, shouldnt have side chrome though. Front wings look slightly flared which is a good sign. Wheels are not Escort, they are Capri Laser.
Have you seen the car in the flesh?
What does the log book say it is?
Check VIN number here:
http://www.rs-garage.co.uk/decode.html
Mexico, RS1600 and RS2000 Mk1 Escorts had type 49 shells ?(similar but not identical to export shells)
How to ID a type 49 shell:
http://www.turbosport.co.uk/showthread.php?p=854826&highlight=type#post854826
The good news:
Even if its not a Mex if its solid, mechanically sounds and is as good as it looks in the photos its a fair price and may be the buy of the century if its a Mex or RS.
If your serious go and see it and take someone who knows early Escorts with you.
Print off the links and give it a good check.
If its a clean usable copy haggle on the price.
If it checks out as a genuine Mexico buy it, sell a kidney if you have to.!