I persevered a bit today and managed to discuss out an old caliper from the shed. Checked part no.s and it just so turned out that the mk1 focus has the same caliper as a st! So these fuckers advertising st calipers second hand for 50 quid are a big con! You can buy brand new calipers for 30 quid! It's not a tried and tested method on my part yet as I'm gonna strip this caliper and see if I can use it first! If I end up buying the focus caliper then I will report back!