Labour's narrow majority following the 1950 UK general election was flattering.
There were huge divisions within the party between the Morrisonian 'right' and the Bevanite 'left'. Unlike in a classic scenario whereby a narrow majority often leads a governing party to close ranks, in 1950-51 Labour publicly fell apart. Prime Minister Clement Attlee had hitherto been a skilful leader bridging the gap between the 2 wings. After 1950, however, he was identified more and more closely with Deputy Prime Minister Herbert Morrison.
The first shot across the bow came from Attlee himself in a cabinet reshuffle in January 1951. Minister for Health Aneurin Bevan 'the father of the National Health Service' was, nevertheless, moved from the Health department to Labour & National Service. An uneasy truce between the Morrisonians and the Bevanites then prevailed until April when things came to a head. The new Chancellor of the Exchequer Hugh Gaitskell brought in a budget which (among other austerity measures) saw the introduction of prescription charges for spectacles and false teeth. This was anathema to the Bevanites with the NHS being barely 3 years old.
And 2 days after the budget, the popular Foreign Secretary Ernest Bevin suddenly died. Attlee appointed Morrison as the new Foreign Secretary while he would also continue to act as Deputy Prime Minister. This was now too much for the Bevanites and after Bevin's funeral had taken place Aneurin Bevan resigned from the government on the following Monday.
With 2 heavyweights of the party, Bevin (a friend) and Bevan (a rival) both gone within the space of a week, the cabinet room must have suddenly felt a very different place for Attlee during the Spring and Summer of 1951. The uneasy atmosphere within the Labour Party was also evident in the House of Commons and beyond. It is probably best summed up by this cartoon by the
Daily Mirror's cartoonist Victor 'Vicky' Weisz from July that year:
Morrison, Attlee and Gaitskell etc are pelted in the street by Bevan, Harold Wilson, Michael Foot and Ian Mikardo.
Labour risked being split down the middle and Attlee decided that he needed to try for a larger majority in order to neutralise the Bevanites. Things couldn't go on as they were and so he went to the country in October. The Tories probably couldn't believe their luck.
P.S. One of the Bevanites (not featured in Vicky's cartoon) was Major John Freeman, MP for Watford. He's still alive in 2013 and at 98 years of age is the oldest living former MP.