Can anyone tell me the name of this plant please

I bought this rockery plant last year and it has a great spread. Unfortunately it is not labelled. Could anyone please tell me its name please. Thank you.

 

Perhaps cerastium tomentosum if it has tiny white flowers in spring/early summer and as you say can spread widely if not kept in check.

 

Thank you for your prompt reply. I will check on this.

 

Is that what is commonly known as snow in summer Fens? if so thats it

 

Behind my greenhouse is now difficult to access, due to the Water Butt and a 6' Trellis.
The 18" space is filled with Snow in Summer and looks pleasant.
There's also Honesty, and something else I can't remember, that grows through the S-in-S later in the year and stands about 3' tall.
The overall effect is Ok and it keeps the weeds down, so it's stayed like this for years.

 

Thank you very much for your reply lolimac. Will go to a garden centre and check.

 

Yes definitely snow in summer, I inherited mine when we moved to this house in 1981 and it's still going strong.

 

Thank you very much gcc.

 

Thank you westwales as well.