spook

Concrete park built on derelict block bordered by Hugh Street, Clara Street and Buddle Road in Benwell.

Here he is - www.theauxiliaries.com/police-advisor-office/haldane/hald...

From thepeerage dot com: Lt.-Col. Maldwyn Makgill Haldane was born on 11 January 1877. He was the son of Robert Camperdown Haldane and Emily Anderson. He married, firstly, Mabel Constance Seymour, daughter of Robert George Seymour, on 8 November 1902. He married, secondly, Katherine Baylay, daughter of Reverend Atwell Mervyn Yates Baylay, in October 1934. He died on 29 June 1940 at age 63. He was educated at St. Paul's School, London, England. He was educated at Loretto School, Edinburgh, Midlothian, Scotland. He was educated at Jesus College, Cambridge University, Cambridge, Cambridgeshire, England. He fought in the First World War. He gained the rank of Major and Brevet Lieutenant-Colonel in the Royal Scots. He was Assistant Director of Special Intelligence Services.

At The Peerage - www.thepeerage.com/p31101.htm#i311005

From the beachcombers link, I think the reason he was of interest to Beaslai and Collins was: 1914 Major, War Office (Declaration of War) Major, Head of H Branch MI5 throughout the war (under Lt. Colonel Kell) 1919 Jan 1 Lt. Colonel, 1920 Lt. Colonel, 1920, A Branch (Director of Administration) Ireland, Dublin Castle. In Police Advisor's Office in Dublin 1922 Lt. Colonel, 1922, Director Criminal Investigation Department (CID), Belfast

Wikispooks [!!] on MI5 history - wikispooks.com/wiki/MI5

Full marks for the camel!

Incredible image ! The kind that leaves you speechless.

Likely Paul Arthur Sorg (died 1913). See comments on another photo of the same scene here.

Got it! We'll add the subject and names.

Companion photo shows Fownes and Sorg up close: Other Bain/LOC photos show the same bracketed Italianate horse barn:

yep, captainslack, something is going on there!