Question
My plant is about two yrs old and has now got light brown on the ends of almost all the older leaves, as if they are dieing off, which appears to be spreading down the leaves. Any ideas please.

Answer
Tony, often times. leaf-tip die off is related to salts which concentrate at the tip of the leaves. When the plant enters a new growth phase (ie when you first see new root growth), repot it in a fir bark based orchid potting mix, being sure to not damage the newly emerging leaves, and discard the old potting mix.  Be sure it is in a pot with lots of drainage holes. If your water has a high mineral concentration (ie "hard" water), mix it 50/50 with rain water. Do not fertilize until the plant is in new growth and, at least once per month, flush the pot thoroughly with rain water.  The flushing should help to remove excess salts from the fertilizer or water.  Also, initially the new potting mix is likely to be dry so soak a portion of it for a couple of hours before using to repot your plant.

The suggestions I have made above will not reverse the damage that has occurred and you may lose some or all of these leaves. You may cut off the unsightly portion of leaves in hopes that this will arrest further damage to those leaves. Before repotting, be sure to remove any damaged roots.  Also remove any pseudobulbs that are soft or spongy before repotting.  New growth should emerge from the base of the healthy pseudobulbs and the new growth should be free of the leaf tip die back as it matures.