It called Lamium galeobdolon, commonly called yellow archangel and spreads quite rapidly. Very pretty yellow dead nettle type flower which the bees adore.
Fairly easy to pull up where you don't want it.

Yes, Lamium . . . quite a useful groundcover plant.

Are you sure that this isn't L. maculatum? I've read that L. galeobdolon is an upright grower.

You could be right Tugbrethil, may well have got the wrong variety, but it's definitely a Lamium.

Pretty sure its galeobdolon. The stems trail flat and the flower stems are upright. Maculatum doesn't send out long trailing stems like that. Fine in a woodland but a pain in a border.

Well, you'll find out for sure when it blooms: L. galeobdolon blooms yellow; and L. maculatum blooms pink, lilac, or white.

No Honeysuckle, you're right. I have both and they are very different..