Weed ID please?

This is spreading in one of my borders.
Seems to be going sideways via the thick root in the pic. It's quite difficult to pull up.

I'm sure I should probably know what it is, but I don't and Google isn't helping. Can anyone put a name to it please?

 

Not a lot to go on, but maybe Rosebay willowherb or Creeping thistle?

 

Have you got a picture of it in situ?

 

No, I pulled it all up before I thought to take a photo unfortunately. I'm sure it will be back though, it's growing pretty quickly whatever it is.

Definitely not rosebay willowherb or thistle though. It has sort of pointy leaves, not spiky like thistle, more like dandelion but with pointed edges.

I'll get another picture as it grows back.

 

Looks like one of the thistles.