I've got an R reg escort and mine did the same, apparently the brake was sticking, causing the juddering, and when it unstuck it drove fine.
The symptoms for mine were exactly as you describe, apparently it's the brake caliper sticking.
I had it front passenger side and it had worn th brake discs so they needed replacing, then a few months later got it in the drivers side and the discs weren't damaged so he just freed it off a little and now it's fine.
Actually i sold it today so no more :P
My clutch was almost dead!
It's likely it's something totally different but your description sounds the same!