Enoch Powell gave the famous "Rivers of Blood" speech on 20 April 1968 in which he warned his audience of what he believed would be the consequences of continued unchecked immigration from the Commonwealth to Britain. Conservative Party leader Edward Heath fired Powell from his Shadow Cabinet the day after the speech, and he never held another senior political post. Powell received 110,000 letters only 2,300 disapproving. Three days after the speech, on 23 April, as the Race Relations Bill was being debated in the House of Commons, around 2,000 dockers walked off the job to march on Westminster protesting against Powell's dismissal, and the next day 400 meat porters from Smithfield market handed in a 92-page petition in support of Powell. At that time, 43% of junior doctors working in NHS hospitals, and some 30% of student nurses, were immigrants, without which the health service would needed to have been curtailed.