Union Jack

— 
Proclamation appointing the Flag, as well for Our Navy Royal as for the Ships of Our Subjects of South and North Britain – 5 May 1634
— 
A Proclamation Declaring His Majesty's Pleasure concerning the Royal Style and Titles appertaining to the Imperial Crown of the United Kingdom of Great Britain and Ireland, and its Dependencies, and also the Ensigns, Armorial Flags, and Banners thereof"
Diagram showing step-by-step construction of the Union Jack Flag, as described in the blazon as decreed by George III of the United Kingdom on 1 January 1801

The three-component crosses that make up the Union Flag are sized as follows:

In South Africa, the Union Jacks flown alongside the National Flag between 1928 and 1957 were 2:3 flags.

azure, the cross saltire of St Andrew argent surmounted by the Cross of St George gules, fimbriated of the second.will breid some heit and miscontentment betwix your Majesties subjectis, and it is to be feirit that some inconvenientis sail fall oute betwix thame, for our seyfaring men cannot be inducit to resave that flage as it is set downThe Ensigns, Colours or Flags of the Ships at Sea: Belonging to The several Princes and States in the World

There was some speculation on the matter in British dominions also, with one New Zealand paper reporting that:

The Union Jack was introduced into South Africa in 1795, and except for the period 1803–06, it was an official flag until 1957.

When the Union of South Africa was established in 1910, the Union Jack was treated as its official flag.