Although the Coalition had won a comfortable majority in the House in 1949, Labor still had a four-seat majority in the Senate. Chifley thus made it his business to obstruct Menzies' agenda at every opportunity. Realizing this, Menzies sought to call a double dissolution at the first opportunity in hopes of gaining control of both houses. He thought he had his chance in 1950, when he introduced a bill to ban the Australian Communist Party. However, after a redraft, Chifley let the bill pass.
A few months later, the Senate rejected the Commonwealth Banking Bill, finally giving Menzies an excuse to call a double dissolution. While the Coalition lost five House seats to Labor, it still had a solid mandate. More importantly, it picked up six Senate seats, giving it control over both chambers.
Prior to 1984 the AEC did not undertake a full distribution of preferences for statistical purposes. The stored ballot papers for the 1983 election were put through this process prior to their destruction. Therefore the figures from 1983 onwards show the actual result based on full distribution of preferences.