St George’s Day is England’s national day – St George was named as England’s principal patron saint in 1416.
St George’s Day is listed as a flag flying day (for England only) by UK government guidance.
https://www.gov.uk/guidance/designated-days-for-union-flag-flying
The Union Flag is specified.
Guernsey celebrates Liberation Day (Lé Jour dé la Libératiaon in Guernsey French) annually on 9 May.
The date commemorates the island’s liberation in 1945 from German occupation during the Second World War.
Jersey celebrates Liberation Day (Jour d’la Libéthâtion in Jersey French) annually on 9 May.
The date commemorates the island’s liberation in 1945 from German occupation during the Second World War.
Sark celebrates Liberation Day annually on 10 May.
The date commemorates the island’s liberation in 1945 from German occupation during the Second World War.
St Helena’s national day commemorates the island’s discovery in 1502 by Galician navigator João da Nova, then serving the King of Portugal.
Anchoring in the present James Bay, da Nova named the island ‘Santa Helena’ after St Helena of Constantinople, whose feast according to the Orthodox Church falls on 21 May.
Bermuda Day first took place as Empire Day on 24 May 1902.
It continued on that day until 2018 when it moved to the fourth Friday in May.
It is also known as Heritage Day, celebrating the island’s culture and heritage.
Anguilla Day takes place annually on 30 May.
On 30 May 1967 the Anguillans began a revolution that led to independence from the union of St Kitts-Nevis-Anguilla.
The Falkland Islands celebrate Liberation Day annually on 14 June.
The date commemorates the liberation of the islands from Argentine military occupation in 1982.
The British Virgin Islands celebrate Virgin Islands Day (formerly Territory Day) annually on 1 July.
This is the date in 1956 when the islands became a separate British Overseas Territory.
The Government of the Virgin Islands changed the name to Virgin Islands Day with effect from 1 July 2021.
https://www.bvi.gov.vg/media-centre/history-culture-and-fishing-mark-virgin-islands-day
The Isle of Man celebrates Tynwald Day (Manx: Laa Tinvaal) annually on 5 July, unless this date falls on a Saturday or Sunday.
In this case Tynwald Day takes place on the following Monday.
