The first is on Sydenham Road, at the corner with Addington Grove. No idea who it is that has planted up a front garden border with phlox, but I think they look great
The second is on my road, where some stocks I grew last year, and allowed to go to seed, seeded themselves in the crack between garden wall and tarmac. The sort of slightly random planting I like
I should think the cracks were already there and the stocks took advantage. They have long stems that bend under obstacles quite happily and are probably rooted well under, in front of or even behind the wall. They won't be rooted in or damaging the wall.
Jaybee - you obviously know Silverdale - but no, some kids, late one evening, ricocheted off that wall and ended with an even bigger bang the other side of the road, closely followed by some police. And that's all I know.