Operation Pigeon Toe: To most of us they're 'flying vermin'. But to some, they're helpless creatures in dire need of rescue from the vast amount of human hair on our streets that wraps around their legs and cripples them

On a wooden bench in a park in east London, a little operating theatre is being set up. Antiseptic creams, powders, sterile swabs, tweezers, nail scissors and a pair of blue latex gloves.