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House of Commons Speaker John Bercow asks if heightism is acceptable

7 July 2014 Last updated at 23:59 BST

David Cameron made a joke that referred to the Speaker of the House of Commons John Bercow as one of the Seven Dwarfs.

Mr Bercow, who is 5ft 6in tall, has questioned why it is somehow acceptable to criticise people over their height, when attacking someone for their skin colour or sexuality is widely accepted as wrong.

BBC Newsnight's Stephen Smith reports.