This letter was addressed to Wm Stewart Esq W.S. North Street(this would be Edinburgh). The addressee may have been the parliamentary agent, or Douglas's solicitor who dealt with his correspondence.
It has 3 postal markings all from Edinburgh. 1) a boxed Receiving House stamp, poorly applied in black in, which is probably CROSS. This was a one of the Edinburgh Receiving Houses, the name stamp was issued in 1829, which is the date of this letter.
2) a faintly applied ‘1 ’ to indicate the Penny postage to be paid
3) the Edinburgh circular date stamp in red ink showing AUG 26 1829 in 3 lines with the E on the right side denoting the evening post, and an illegible letter on the left to identify the actual handstamp. It has been placed across the fold of the letter.
It has filing note on the outside, which is upside down on this image.
‘Chas. Gordon Esq Highld Society 6 Aug 1829 Mr K Douglas’s subscn.’
So now to the letter, which is a reminder of the subscription dues.
Circular
Highland Society Hall
Edinr. 6th August 1829
Sir,
I beg leave to remind you that your annual Subscription of £1. 3. 6d as a Member of the Highland Society of Scotland, due in January last, has not been paid. Should you incline to purchase a Life Subscription the sum you would have to pay would at present amount to only £7. 1/- including the annual payment now due.
Please to order payment to me here in either way most agreeable to you.
I have the honor to be
Sir,
Your most obedient Servant
Charles Gordon D. Secy
William R. Keith Douglas Esq M.P.
As this letter noted that he was an MP, I checked the internet and found this information from Wikipedia.
Lord William Robert Keith Douglas (b. 1783 d.5 December 1859) was a British politician and landowner. He was the fourth son of Sir William Douglas, 4th Baronet of Kelhead and younger brother of both Charles Douglas, 6th Marquess of Queensberry and John Douglas, 7th Marquess of Queensberry. He represented the Dumfries Burghs constituency between 1812 and 1832 and served, on a number of occasions, as one of the Lord Commissioners of the Admiralty. He owned sugar plantation estates in Tobago which had formerly belonged to Walter Irvine, whose daughter, Elizabeth, he married on 24 November 1824. They had three sons, the second of which, Walter, went on to continue the Douglases of Grangemuir.
In May 1837, some time after William Douglas's eldest brother succeeded to the Marquessate of Queensberry, he was granted a patent of precedence which gave him the rank and style of a Marquess's younger son (Lord William Douglas).
(In other words he was not Lord William until 1837, not at the time this letter was written, his title then was William R. Keith Douglas Esq M.P.)
Lord William is buried at Dunino, Fife, a village close to his family seat at Grangemuir, near Pittenweem, and of course I have no idea whether he paid his subscription to the Highland Society.