The continued use of the Union Jack as national flag became an issue in the 1920s, when the government proposed to introduce a National Flag of the Union. A compromise was reached in which both flags were flown on official buildings. The Union Nationality and Flags Act 1927 provided that the flags of the Union were (a) the Union Jack, to denote the association with the other members of the British Commonwealth of Nations, and (b) the new National Flag. The Union Jack was to be flown alongside the National Flag at the Houses of Parliament, from the principal government buildings in the capitals, at Union ports, on government offices abroad, and at such other places as the government might determine. This dual arrangement was effective from 31 May 1928.