I thought this was a bit of an urban find. I think that's wheat and it's growing in a tiny patch of garden at the end of the the mews.
I'm wondering how it got there. Breadcrumbs dropped from birds maybe. Or there's an artisan bakery over the road. Maybe some seeds blew over from there but I'm not sure they're the sort of seeds that would blow around.
It's all a bit of a mystery.