Most Conservative governments in the 20th century couldn’t really be said to have positively increased workers’ rights. Indeed, some of them actually eroded them – most obviously the Thatcher government but also, one could argue, the Baldwin government (with its post- General Strike 1927 Trades Disputes Act) and the Heath government (with its 1971 Industrial Relations Act actually provoking resistance that saw a handful of trade unionists sent to prison).
This couldn’t be said, though, of Tory governments of 1951 to 1964, which much to the irritation of the party’s free-market right, were renowned not so much for increasing workers’ rights but for (i) refusing to bow to demands to roll back the Attlee government’s pro-trade union legislation, (ii) interfering in pay disputes in order to facilitate compromise, and (iii) moving towards corporatist-style tripartite structures aimed at bringing management, unions and the state together to help plan the economy.
If you want to go back before then – and for the Tory government that probably did more than any other to positively promote workers’ rights (not least because it was competing with the Liberal Party for the votes of newly enfranchised working men, of course) – you’d have to go for Disraeli’s second government.
Dizzy’s administration passed, for instance, the Factory Acts in 1874 and 1878, which declared, among other things, that no child under ten could be employed, that 10-14 year olds could only work half-days, and that there would be a limit (albeit a very high one) on the working week for women. It also passed the 1875 Conspiracy, and Protection of Property Act 1875 which legalised peaceful picketing, as well as the 1875 Employers and Workmen Act which meant that workers could sue employers for breach of contract.
It’s worth remembering, however, that we’re comparing what past Tory governments actually did with what Mrs May says she is going to do. The proof of the pudding will, as always, be in the eating!