The Representation of the People Act 1918 took account of new local government boundaries in definitions of new constituency boundaries, and the Kinross and Western Perthshire constituency was defined as covering the county of Kinross and the Central, Highland and Western districts of the county of Perth, including the county of Perth burghs of Aberfeldy, Auchterarder, Callander, Crieff, Doune and Dunblane.[2]
For the February 1974 general election, as a result of the Second Periodical Review of the Boundary Commission, there were minor alterations to the boundaries of the Kinross and West Perthshire constituency and the Perth and East Perthshire constituency. Kinross and West Perthshire was defined as covering the county of Kinross and the Central, Highland and Western districts of the county of Perth, including the county of Perth burghs of Aberfeldy, Auchterarder, Callander, Crieff, Doune, Dunblane and Pitlochry.[2]
February 1974 boundaries were used also in the general elections of October 1974 and 1979.
New constituency boundaries, taking account of new local government boundaries, were adopted for the 1983 general election. Constituencies defined to cover the Tayside region included Perth and Kinross, and constituencies designed to cover the Central region included Stirling.
Another General Election was due to take place before the end of 1940. The political parties had been making preparations for that election and by autumn 1939, the following candidates had been selected: