Over the past few days, the plant in question has developed a purplish/brown
mottling over all the leaves, except the growing tip. I thought that I had come
across most things that plants suffer from but this has left me guessing. When
an infected leaf is turned over it does not show, so I guess that the condition
only affects the upper tissues of the leaf. Any Ideas!! I have kept one leaf,
but have binned the plant, soil, label, and pot. (Im taking no chances). Picture
of affected leaf below.