Hi Hales and welcome to GoY this grass is deciduous so not surprised at it looking dead right now. You'll need to get planted somewhere in fill sun if possible.

And in moist soil

Depending on where abouts in the UK you are - this grass is not fully hardy. I've tried and failed with it a few times in a normal winter here in Edinburgh.

Meanwhile, here in Berkshire, I've had it for nearly 20 years

What a difference a few hundred miles makes Andrew :)

I failed in Pembrokeshire, but may have been through ignorance as it wasn't planted in a moist sunny spot.

Your grass will be fine, Hales . . . ours looks exactly like this in winter. Best to plant it in gravel or similar (ours is in a whitish stony bed), as it completely disappears from sight, and in a border can easily be forgotten or overlooked. Cut the brown growth back completely in early Spring as soon as you see the new green shoots.