Posted: 10/06/2015 at 23:33
I've heard Linaria vulgaris, aka toadflax called wild antirrhinum. I don't think that's what you've got there.
I should think it's a descendent of antirrhinums previously grown in the garden. Has the top growth all broken off from the root? If so it might be worth seeing if there's regrowth but they are short lived as perennial, some people consider themto be annuals. You may find seedlings appear to take its place if you've allowed it to seed in previous years. I hope it works, it's a fine plant