I believe it's a Speedwell. If left to bloom it will bear blue flower spikes. I had it in my previous garden where it popped up in all sorts of places. If you don't like it you can dig it up fairly easily.

Agree with Arbuthnot . . . mine has 'lilac' coloured flowers and seeds itself around, so I leave it where I like it and pull out the rest.

its not a speedwell its Linaria purpurea, a perennial toadflax. it may have pink or white flowers though the usual colour is purple. I rather like it and have some in garden. it seeds freely and may become a pest/weed. so if you like it keep it. if not hoick it out.
welcome to GoY too

I've been wracking my brain all day for the name of this plant - I knew it started with an L but it just wouldn't come to me. I have one, which has travelled with me from my old garden and I think it's a very cheerful flower which the bees adore.

Well done Seaburn . . . I thought it wasn't Speedwell, but couldn't for the life of me think what it was. Glad you've sorted it for us :)

My neighbour gave me a root of this and I love it. I think the common name is purple toadflax but not sure. Bees love it, as Cammomile says, which is why I wanted it. It does self-seed and puts down strong roots but is easily dug up and transplanted. Very pretty.

I love the yellow one too - grows wild locally. Does the purple one grow wild in the UK?

as a garden escapee it does yes.

i didn't think it was a native - pity, its very pretty.