Aye Up Robson valley,
No, the form and colours are far from unusual - it is very typical not just of the specific woodland that the image was taken in but over a wide area.
The colour palette can be found not just in woodland proper but in field boundaries, coppices etc.
Depending on the weather temp and amount of precipitation, we can often get a prolonged period of brown leaf-fall and fern-turned-bracken giving a very olive and brown palette in a lot of our woodland - tree trunks and ground cover.
But I understand where you are coming from re grey - many years back before they were even available on the commercial market we received some leaf blankets produced in the
US which our suppliers believed would be the ultimate in cam & concealment - in the event when set up against a variety of different backgrounds here they came out as too light
and/or too grey. In fact the colours only came anywhere near to working when we turned them over but that lost the 3D effect.
On the subject of grey we do use it and I have previously mentioned it on here in a couple of posts. It has regularly proven very effective even in environments like the one in the image.
There is some science behind it (ask the squirrels) along the lines of the human brain somehow superimposing surrounding and back ground colours onto smaller, irregular areas of grey.
I have frequently had success with the Austrian 'stone-grey' - a sort of olive-grey, in woodland, particularly during the winter months.