During the 50 years that The Week in Westminster has been on the air. British politicians and broadcasters have developed a remarkable and unique relationship. Occasionally, as at the time of the Suez crisis in 1956, this has almost amounted to open warfare. Robert Carvel has been tracing the ups and downs of what he calls ' the odd couple ', with the help of those involved, including the Home Secretary, The Rt Hon William Whitelaw , MP, and the BBC's Director-General, Ian Trethowan. Producer CAROLINE MILLINGTON