[[Súbor:Flag of the United Kingdom.svg|thumb|Vlajka Spojeného kráľovstva]]
'''Vlajka [[Spojené kráľovstvo|Spojeného kráľovstva]]''' – známyznáma ako „''Union Jack''“<ref>[http://www.flaginstitute.org/wp/british-flags/the-union-jack-or-the-union-flag/ The Flag Institute]: "It is often stated that the Union Flag should only be described as the Union Jack when flown in the bows of a warship, but this is a relatively recent idea. From early in its life the Admiralty itself frequently referred to the flag as the Union Jack, whatever its use, and in 1902 an Admiralty Circular announced that Their Lordships had decided that either name could be used officially. Such use was given Parliamentary approval in 1908 when it was stated that 'the Union Jack should be regarded as the National flag'."</ref>, má svoju dnešnú zložitú podobu z roku [[1801]]. Vyvíjala sa však dlhú dobu a zobrazuje históriu [[Spojené kráľovstvo|Spojeného kráľovstva]], pretože obsahuje vlajky [[Vlajka Anglicka|Anglicka]], [[Vlajka Škótska|Škótska]] a [[Vlajka Írska|Írska]].
