The Munitions of War Act was passed in 1915 and gave the newly created Ministry of Munitions power to declare factories controlled establishments and restrict the freedom of workers to leave, through a system of certificates and of tribunals.
The Ministry was given power to regulate wages in the industry in 1916. Strikes in war industries were made illegal and labour disputes went to compulsory tribunals. In practice, strikes continued in the UK throughout the war.
The concern that lower wages paid to women engaged in munition work would prejudice the position of skilled men returning from the war is made clear in this response from the Minister, Lloyd George, on 21 October 1915:
"It would be a violation of the spirit and the letter of the Munitions Act if the employment of women or unskilled men on munitions work should be utilised for the purpose of lowering the remuneration of men customarily engaged on that class of work."
The proportion of women in total employment rose from 24 per cent in July 1914 to 37 per cent by November 1918. Women had proved themselves in the workforce, a factor in earning them the vote, but after the war employment levels fell back.