Ok found a digital camera to use, have lost my pH indicating solution so no soil pH as of yet, hopefully this'll help the diagnosis
The first 2 show leaves that have shriveled and died (there are i think 4 of these leaves altogether) the second two are showing the yellow leaf, this partivular leaf is the worst affected at this stage, theres maybe 2-3 of these per plant (of the 4 others) at different stages. The second last pic is of 1 of the newer plants whose leaf is beginning to yellow. The last pic is of the 6 plants together a view from the top to show how the yellowing hasnt spread, and also for comments on the plants themselves
EDIT: In the group shot the 2 newer plants are the two centre plants.