The photographer who documented Britain's disability rights movement from the inside has finally been recognized, and his archive is free to use

A wheelchair user in a pink sweatshirt holds a sign reading "How about us?" beside a red London Leyland bus, as bystanders look on from the pavement.

There's a photograph in Keith Armstrong's newly discovered archive that stops you in your tracks. A man in a wheelchair grins defiantly, surrounded by Metropolitan Police officers. A red London bus looms behind him, its destination board reading Trafalgar Square. It's the kind of image that could have run on the front page of a national newspaper.

Actually though, it didn't; because Armstrong (1950-2017) wasn't a press photographer filing for an agency. He was a disability rights activist, shooting from his wheelchair, from inside the demonstration, for the movement itself.