The flag of the UK is officially called the Union flag, because it embodies the emblems of three countries united under one monarch. The Union Flag is commonly known as the Union Jack, although the exact origin of the name is unclear. One explanation is that it gets its name from the "jack staff" of naval vessels (a small flagpole at the front of Royal Navy vessels) from which the original Union Flag was flown. The Union Flag should be flown with the broader diagonal band of white uppermost in the hoist (near the pole) and the narrower band of white uppermost in the fly (furthest from the pole). The emblems that appear on the Union Flag are the crosses of the three patron Saints:
- the white diagonal cross, or saltire, of St Andrew, for Scotland, on a blue ground;
- the red cross of St George, for England, on a white ground;
and
- the red diagonal cross attributed to St Patrick, for Ireland, on a white ground.
Proportions - 1:2.
(Source: 10 Downing street, http://www.pm.gov.uk)