The by-election took place during the Second World War. Under an agreement between the Conservative, Labour and Liberal parties, who were participating in a wartime coalition, the party holding a seat would not be opposed by the other two at a by-election. Accordingly, it fell to the Cardiff East Conservatives to choose the successor to Temple-Morris and they unanimously selected Sir James Grigg at the request of Conservative Central Office. Grigg had been a career civil servant, had served at the Treasury and in India and had risen to become Permanent Under-Secretary of State at the War Office. In this role he worked closely and effectively with Sir Alan Brooke the Chief of the Imperial General Staff and in 1942, in an unorthodox move, the Prime Minister Winston Churchill appointed Grigg Secretary of State for War as a replacement for David Margesson whom he dismissed after the fall of Singapore to the Japanese. The timing of Temple-Morris’ appointment as a judge, albeit to replace one who had died, thus creating a vacancy in Cardiff East, the appointment of Grigg as War Secretary necessitating his finding a seat in the House of Commons and the ease with which the Cardiff Tories selected Grigg as their candidate at the behest of party headquarters even though, as he admitted himself, he had no previous connection with the constituency or the Conservative Party strongly suggests that the whole process was engineered by the government. Underlining his lack of party political credentials, Grigg stated that he intended to stand in the by-election as a National candidate without other party label. He said that as a civil servant of 30 years standing it would be unfair to the service to adopt a party affiliation and he said he had none. He declared that he wanted to be the party of national unity at a time of national emergency and that the war had to be won as a nation not by any party ticket.
The main election issue was the prosecution and conduct of the war. Grigg declared his support for the armed forces and his plans to improve equipment and training and he promised to continue to develop new weapons and devices by involving scientists in the war effort. He urged the press to cease attacks on the military leadership and the performance of the armed forces, accusing those parts of the media who did so of doing Hitler’s work. In his election address Grigg wholeheartedly associated himself and his candidacy in the by-election with the fight to rid the world of Nazi and Japanese domination and to build from the wreck of the old world a better and more just new one with equality of opportunity for all. Grigg also fired a similar salvo at Brockway, claiming that he was opposed to Britain's fighting the war and warned that unless Brockway was defeated decisively, Britain's enemies would be encouraged. In his election address, Brockway stated that the policy of a socialist Britain would not be to negotiate with Hitler but to appeal to the peoples of Europe to overthrow him. The ILP campaign emphasised the importance of socialism and the need for solidarity with the Soviet Union. However the Communists were said to be supporting the National candidate and they accused the ILP of trying to sabotage the united front against fascism. The Labour movement through the local organising secretary of the Transport and General Workers Union, John Dooley, also made clear their support of Grigg in line with official Labour Party policy.
The result
Grigg was returned comfortably with 75% of the poll, albeit on the relatively low turnout of 33%. The by-elections of the Second World War showed evidence of the role of the war in initiating a leftward swing in British politics so pointing the way towards the coming electoral landslide for Labour in 1945. They also offered voters an opportunity to rebel against the electoral truce as the success of Common Wealth and Independent candidates in a number of wartime by-elections showed. However, Cardiff East was not one of these elections. A genuine cross party backing for the non-partisan figure of Sir James Grigg, a patriotic desire to support Grigg in his vital position of Secretary for War and the perception of the ILP as an extremist and anti-war organisation, all combined to ensure that Cardiff East bucked the anti-government trend of a number of mostly later by-elections.
