Looks like Linaria purpurea - this often pops up on its own as a 'weed' but you can buy named varieties such as 'Canon Went', see link for more info

https://www.rhs.org.uk/plants/details?plantid=1172

Agree Linaria. You don't need to get more as it will seed around, produce various colour forms and in a year or three you might well be considering a weed. It is an attractive plant but I would recommend not allowing it to seed after this year, you will then have plenty in the garden.

Yep that's it. I share a drive with four other houses and have taken it on....it's four inches of poor topsoil and concrete and builders rubble underneath. Nearly everything struggles but this plant seems to thrive. Bees love it too.
Thanks guys.