I've moved on to the damsons now and Im still having problems.
Batch 1 : I followed Vals recipe using 1:1 fruit to sugar. It set so hard I couldn't even get the spoon into it. Seemed to require very little boiling before thickening alarmingly.
Batch 2 : 1:0.75 its still running around the jar. Boiled for 20 mins, when I tested on a cold plate it formed a skin and wrinkled up.
I don't get it - there are only 3 stages at this rate the cupboard will be full of jam-ish rather than jam.