Know your flags

A little Christmas teaser. Do you know your flags? Then what flag is this? Where and when would you have flown it?
The answer is a British ship on the sea between 1606 and 1800
This is the original version of the Union Flag. When King James VI of Scotland ascended to the English throne, thereby becoming James I of England, on land the national flags of England and Scotland continued to be, respectively, the red St George's cross and the white St Andrew's cross. Confusion arose, however, as to what flag would be appropriate at sea. On the 12th April 1606 a proclamation was issued:
"All our subjects in this our isle and kingdom of Great Britain and the members thereof, shall bear in their main top the red cross commonly called St George's Cross and the white cross commonly called St. Andrew's Cross joined together according to a form made by our heralds and sent to our Admiral to be published to our said subjects."
This is the first reference to the Union Flag and, although the original design referred to has been lost, it is presumed that it was the flag which, with the addition of the St Patrick's cross forms the basic design of the British Union Flag as it is today.
The modern version was adopted on the 1st January 1801
"Admiralty Office, 15 November 1800.
Gentlemen,
A Report from the Lords of the Committee of the whole Council, dated 4th instant etc., etc. [details of decision to issue a Royal Proclamation]
That the Committee were further of opinion that the Union Flag should be altered according to the Draught thereof marked (C) in which the Cross of St George is conjoined with the Crosses of St Andrew and St Patrick:
And that the Standard be the Arms of the United Kingdom according to the Draught marked (B);
And that on and after the First Day of January next ensuing the said Flags and Banners should be hoisted and displayed on all His Majesty's Forts and Castles within the United Kingdom, and the Islands of Guernsey, Jersey, Alderney, Sark, and Man, and also on board all His Majesty's Ships of War, then lying in any of the Ports or Harbours of the said United Kingdom, or of the Islands aforesaid, and on board His Majesty's Ships employed on Foreign Service, as soon after the said First Day of January next as His Majesty's Proclamation or Order in Council shall be received by the Commanders of His Majesty's Ships employed on Foreign Service; We herewith transmit to you a Printed Copy of His Majesty's Order in Council of the 5th instant approving the Report of the Lords of the Committee afore-mentioned, and do hereby desire and direct you to cause such Flags and Standards as may be necessary to be prepared conformably to the said Draughts for the use of His Majesty's Ships of War at Home and on Foreign Stations, and to be supplied with them accordingly, with all the dispatch that may be.
You are also to cause the Colours described in the said Order in Council to be hoisted in all the Dock Yards of the Kingdom upon the 1st Day of January next, and to supply the necessary Colours for the use of the Naval Hospitals at Home, and the Naval Yards and Hospitals abroad, in the manner directed by the said Order in Council;
We are Your affectionate Friends,
Arden, J.Gambier, W.Young. Navy Board."
The Second Royal Proclamation that followed the 1801 Act for the Union of Great Britain and Ireland included the following:-
"And to the End that none of Our Subjects may presume, on board their Ships, to wear our Flags, Jacks, and Pendants, Which, according to ancient Usage, have been appointed as a Distinction to Our Ships, or any Flags, Jacks, or Pendants in Shape and Mixture of Colours so far resembling Ours as not to be easily distinguished therefrom, We do, with the Advice of Our Privy Council, hereby strictly charge and command all Our Subjects whatsoever, that they do not presume to wear in any of their Ships or Vessels, Our Jack, commonly called the Union Jack, nor any Pendants, nor any such Colours as are usually borne by Our Ships, without particular Warrant for their so doing from Us, or Our High Admiral of Great Britain, or the Commissioners for executing the Office of High Admiral for the Time being: And We do hereby also further Command all Our loving Subjects, that without such Warrant as aforesaid, they presume not to wear on board their Ships or Vessels any Flags, Jacks, Pendants, or Colours, made in imitation of, or resembling Ours, or any Kind of Pendant whatsoever, or any other Ensign than the Ensign, described on the Side or Margin hereof which shall be worn instead of the Ensign before this Time usually worn in Merchant Ships;"
So now, if you get stopped by the Border Agency, you will know what to say.
With thanks to Flags of the World