Sherlock Holmes Society of London: We meet at Waterloo Place, just off Pall Mall, where Marcus Geisser briefs us (photo by Roger Johnson)
Sherlock Holmes Society of London: Even for as sedentary a man as Mycroft Holmes, the walk to the various government offices in Whitehall would not be too arduous (photo by Roger Johnson)
Sherlock Holmes Society of London: Only a short distance away is St James's Palace, where foreign ambassadors are accredited at The Court of St James's (photo by Roger Johnson)
Sherlock Holmes Society of London: Watson is first told that Mycroft "audits the books in some of the government departments" (photo by Roger Johnson)
Sherlock Holmes Society of London: Much later, Watson learns that occasionally Mycroft IS the British government! (photo by Roger Johnson)
Sherlock Holmes Society of London: Much of Mycroft's time would be spent at the Foreign Office - so that's where we're going! (photo by Roger Johnson)
Sherlock Holmes Society of London: We walk past Horse Guards Parade, which is being prepared for the Trooping of the Colour (photo by Roger Johnson)
Sherlock Holmes Society of London: The Queen's actual birthday is in April, but her Official Birthday is celebrated with impressive pageantry in June (photo by Roger Johnson)
Sherlock Holmes Society of London: On the other side of Horse Guards Road is St James's Park, where a heron perches on the turret of Duck Island Cottage (photo by Roger Johnson)
Sherlock Holmes Society of London: Beyond the lake we get a glimpse of Buckingham Palace (photo by Roger Johnson)
Sherlock Holmes Society of London: Our guide Graham explains that in Mycroft's time this was the Foreign and Colonial Office, incorporating the India Office (photo by Roger Johnson)
Sherlock Holmes Society of London: The India Office Council Chamber was designed by Matthew Digby Wyatt in the 1860s (photo by Roger Johnson)
Sherlock Holmes Society of London: In this room the governance of the Indian sub-continent was decided (photo by Roger Johnson)
Sherlock Holmes Society of London: The chimney piece and overmantel are the work of the Flemish sculptor Michael Rysbrack and date from 1730 (photo by Roger Johnson)
Sherlock Holmes Society of London: Graham indicates the centre panel, representing Britannia, seated by the sea and receiving the riches of the East Indies (photo by Roger Johnson)
Sherlock Holmes Society of London: In the India Office Council Chamber our guide tells us something of the turbulent history of the British Raj (photo by Roger Johnson)
Sherlock Holmes Society of London: After the Sepoy Mutiny of 1857-58, the British government took over direct control of India from the East India Company (photo by Roger Johnson)
Sherlock Holmes Society of London: Lord Cornwallis is remembered as a British General in the American War of Independence. From 1786 to 1793 he was Governor-General of Bengal (photo by Roger Johnson)
Sherlock Holmes Society of London: The Reception Suite (now the Locarno Suite) was designed by George Gilbert Scott for diplomatic dinners, conferences and receptions (photo by Roger Johnson)
Sherlock Holmes Society of London: David Jones & Catherine Cooke seem at home in the Conference Room of the Locarno Suite (photo by Roger Johnson)
Sherlock Holmes Society of London: The Conference Room was intended by Scott as "a kind of national palace, or drawing-room for the nation" (photo by Roger Johnson)
Sherlock Holmes Society of London: A group photo in the Locarno Conference Room, taken by our obliging guide, Graham (photo courtesy of Roger Johnson)
Sherlock Holmes Society of London: The Reception Suite was renamed the Locarno Suite in 1925, after the Locarno Treaties were signed there (photo by Roger Johnson)
Sherlock Holmes Society of London: The Locarno Grand Reception Room (photo by Roger Johnson)
Sherlock Holmes Society of London: The magnificent ceiling of of the Locarno Grand Reception Room was painstakingly restored in the early 1990s (photo by Roger Johnson)
Sherlock Holmes Society of London: After extensive restoration, the Locarno Suite is once more used for conferences and ministerial and government functions (photo by Roger Johnson)
Sherlock Holmes Society of London: From the palatial Locarno suite, Graham takes us to a minister's rather splendid office (photo by Roger Johnson)
Sherlock Holmes Society of London: Not all these splendid doors lead to corridors or other rooms; some merely give access to cupboards! (photo by Roger Johnson)
Sherlock Holmes Society of London: The double doors ensure that two distinguished visitors can enter with equal status (photo by Roger Johnson)
Sherlock Holmes Society of London: The golden figure above the overmantel holds a plaque with the name 'India' (photo by Roger Johnson)