Lancashire Day has taken place annually on 27 November since 1996.
It commemorates the day when Lancashire first sent representatives to Parliament, the Model Parliament of King Edward I (1295).
Bedfordshire Day takes place annually on 28 November.
The date, chosen by popular vote, commemorates the birthday of John Bunyan.
Several alternative options included:19 January – earldom (later dukedom) of Bedford recreated (1550); 12 April – Bedfordshire County Council granted its coat-of-arms (1951); 20 June – siege of Bedford Castle begins (1224); 13 August – Blenheim Day, celebrated by the Bedfordshire Regiment and its successors; 12 September – birth of prison reformer John Howard (1726); 14 October – first flight of the airship R101 from Cardington (1929); 6 November – 1st and 2nd Battalions Bedfordshire Regiment meet at Bailleul en route to Ypres (1914); 15 November – first High Sheriff of Bedfordshire appointed (1575); 25 November – feast of St Catherine, patron saint of spinners, weavers and lacemakers; 15 December – birth of Olympic athlete Harold Abrahams (1899).
Caernarfonshire Day takes place annually on 28 November.
It commemorates the death of Prince Owain Gwynedd, King of Gwynedd (1137–70).
The birthday of the Duchess of Rothesay (Princess of Wales) is an official flag flying day only in Scotland, not in the rest of the UK.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
The birthday of the Duchess of Edinburgh (and Countess of Forfar) is an official flag flying day only in Scotland, not in the rest of the UK.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
St David’s Day is Wales’ national day.
The Senedd Cymru flies the Welsh national flag – Y Ddraig Goch (The Red Dragon) – all year round.
On St David’s Day it also flies the flag of St David (below).
https://senedd.wales/media/hl5dtuct/foi-574-final-redacted-response-saes.pdf
St David’s Day is also listed as a flag flying day (for Wales only) by UK government guidance.
The Union Flag is specified.
https://www.gov.uk/guidance/designated-days-for-union-flag-flying
St Piran, the patron saint of tin miners, is one of Cornwall’s patron saints.
St Felix (d.647/8), the first bishop of the East Angles, introduced Christianity to the kingdom.
Commonwealth Day is the second Monday in March.
The UK government states that the Union Flag should be flown.
https://www.gov.uk/guidance/designated-days-for-union-flag-flying
The Scottish government states that the Commonwealth flag should be flown.
https://www.gov.scot/publications/flag-flying-on-government-buildings/
The Senedd Cymru states that the Commonwealth flag should be flown.
https://senedd.wales/media/hl5dtuct/foi-574-final-redacted-response-saes.pdf
The birthday of the Duke of Edinburgh (and Earl of Forfar) is an official flag flying day only in Scotland, not in the rest of the UK.
https://www.gov.scot/publications/flag-flying-on-government-buildings/