Looks like Aureola Japanese Forest Grass or 'Golden Japanese Forest Grass'.

Its Hakonechloa macra 'aureola' if you're looking to buy it - link here

https://www.crocus.co.uk/plants/_/hakonechloa-macra-aureola/classid.2000011921/

They are not evergreen, disappearing below ground for winter.

That's exactly what I just said, lol!

http://www.finegardening.com/plant/golden-japanese-forest-grass-hakonechloa-macra-aureola

Many thanks. Much appreciated. Didn’t realise they died back in winter. But I still may purchase a few.

I think it's beautiful chartreuse - love the feathery texture & how it moves in the wind. Makes a nice statement in the border. I have Liriopi (monkey grass) which is somewhat similar but sends up blue flower spikes.

Sorry just another question. Would you recommend putting 3 /5 plants evenly spaced together to get that effect. Thanks

I would space them at least 12 inches apart. They'll spread fairly quickly.

Yes just looked at the Monkey Grass and it’s beautiful. Is it invasive?

Well, a healthy plant is gonna want to spread, but I wouldn't say 'invasive'. I take divisions every couple years.

Liriope isn't invasive here. in fact I struggle to get it to flower.

Me too. I think it needs regular feed and water, not something it gets here.

Beautiful grass . . . have a look at Hakonechloa macro too: same cascading habit but a lovely green.