[jarek]

Strictly speaking, flying kites is not allowed in other London streets as well ("any street, to the obstruction, annoyance, or danger of the residents or passengers", from a 19th century law http://www.legislation.gov.uk/ukpga/Vict/10-11/89/section/28). Flying a kite from the pavement of Waterloo Bridge seems intuitively a bad idea so that's not very controversial. It does undermine their "park" claims though...