Possibly underwatering, assuming its in a pot and the pot has drainage. The other problem might be from the extremely hot and sudden heatwave we had, which might have burnt the needles after such a long time with very dull weather and low uv light levels.

Thans bamboo - actually it's in the ground - maybe I have a drainage issue as I think the soil may be to clay like ? Not sure that it's the heatwave as it started happening before this - who knows.

Not sure clay soil will be an issue - this one likes moist but not waterlogged, rich, fertile soil, so with a bit of enrichment with humus rich material at planting time, and as a mulch over time, clay soil should be fine.
If this started before the heatwave, that knocks that explanation on the head, but I've done a bit more reading - it hates wind, specially cold wind, so needs to be in a very sheltered, sunny spot. Given we now get a lot more wind in this country than we used to, and at all times of year, could it be that?

Thanks once more Bamboo - really nice of you to go to all this trouble.

Maybe it is the wind - not really sure - I didn't realise that that could make the needles go brown - let's see what happens when the sun comes out again ?

Ah, and when might that be, Richard... I've forgotten what sunshine looks like.

True - makes you want to emigrate !