Use in other flags
International Settlement of Kulangsu (Gulangyu, China)
http://www.crwflags.com/fotw/flags/cn-kul.htmlFlags of the World (website) - Wikipedia
https://en.wikipedia.org/wiki/Flags_of_the_World_(website)Westmoreland County, Pennsylvania (U.S.)
http://www.crwflags.com/fotw/flags/us-pa-wc.html
Status outside the United Kingdom
SOUTHERN AFRICAN VEXILLOLOGICAL ASSOCIATION
http://www.savaflags.org.za
Status in the United Kingdom
UK Flag Protocol | Free online guide | With illustrations | The Flag Institute
https://www.flaginstitute.org/wp/british-flags-2/flying-flags-in-the-united-kingdom/british-flag-protocol/#index29United Kingdom
http://www.crwflags.com/fotw/flags/gb.htmlFlags of the World (website) - Wikipedia
https://en.wikipedia.org/wiki/Flags_of_the_World_(website)Canadian Flag Etiquette
http://www.crwflags.com/fotw/flags/ca_prtcl.htmlTHE FLYING OF THE UNION JACK (Hansard, 14 July 1908)
http://hansard.millbanksystems.com/lords/1908/jul/14/the-flying-of-the-union-jackUNION FLAG. (Hansard, 27 June 1933)
http://hansard.millbanksystems.com/commons/1933/jun/27/union-flagWayback Machine - Wikipedia
https://en.wikipedia.org/wiki/Wayback_MachineHouse of Commons Hansard Debates for 05 Feb 2008 (pt 0004)
https://web.archive.org/web/20161026002232/http://www.publications.parliament.uk/pa/cm200708/cmhansrd/cm080205/debtext/80205-0004.htmPlease Wait... | Cloudflare
https://publications.parliament.uk/pa/cm200708/cmhansrd/cm080205/debtext/80205-0004.htm
History
United Kingdom
http://www.crwflags.com/fotw/flags/gb.htmlFlags of the World (website) - Wikipedia
https://en.wikipedia.org/wiki/Flags_of_the_World_(website)United Kingdom: lighthouse authorities
http://www.crwflags.com/fotw/flags/gb-lthse.html#cnlcBBC News | Enlarged Image
https://web.archive.org/web/20210410134721/http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/06/magazine_enl_1144679591/html/1.stmBBC News | Enlarged Image
http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/06/magazine_enl_1144679591/html/1.stm
Design
United Kingdom - variant flag dimensions
http://www.crwflags.com/fotw/flags/gb_var.html#35Flags of the World (website) - Wikipedia
https://en.wikipedia.org/wiki/Flags_of_the_World_(website)United Kingdom
http://www.crwflags.com/fotw/flags/gb.html
Terminology
Flags of the World (website) - Wikipedia
https://en.wikipedia.org/wiki/Flags_of_the_World_(website)United Kingdom
http://www.crwflags.com/fotw/flags/gb.html
Union Jack
Category:Coats of arms of King Henry VII of England - Wikimedia Commons
https://commons.wikimedia.org/wiki/Category:Coats_of_arms_of_King_Henry_VII_of_EnglandBBC - Wikipedia
https://en.wikipedia.org/wiki/BBCRoyal Navy - Wikipedia
https://en.wikipedia.org/wiki/Royal_NavyJackstaff - Wikipedia
https://en.wikipedia.org/wiki/Jackstaff