When I spotted these plants during a walk to a new place last week, I thought perhaps they were Sea asters (Tripolium pannonicum) and, indeed, they might be, but I’ve since heard how frequently other species of Aster self-seed on waste ground, which has cast doubt on my identification. These were growing in rough ground near a very busy road but quite close to the banks of a tidal creek. I’m going to have to ‘phone a friend’ but, in the meantime, if you’re familiar with Sea aster, please do venture an opinion in the comments.