This is our 'thug'...could anyone identify it please?

I planted one many years ago and no matter how many I pull up it always reappears, I believe it is Carex laxiculmis (spreading sedge).

I thought carex, too. It must be spreading: we've just dug a load out of a border. It flew in from next door, I think. A good plant in the right place!

certainly a Carex. they self seed very freely. I have C comans 'Bronze'.