The London Controlling Section (LCS) was a British secret department established in September 1941, under Oliver Stanley, with a mandate to coordinate Allied strategic military deception during World War II. The LCS was formed within the Joint Planning Staff at the offices of the War Cabinet, which was presided over by Winston Churchill as Prime Minister.

At first the department struggled to have any impact, and Stanley spent time away from the office due to his wife's terminal illness. In June his post of Controlling Officer was handed over to Colonel John Bevan, who managed the LCS until the end of the war.

The organisation was publicly revealed by Sir Ronald Wingate in 1969.

Following the onset of the Second World War, the Allied nations began to recognise deception as a useful strategy. In early 1941 Lieutenant-Colonel Dudley Clarke's 'A' Force department, based in Cairo, undertook deception operations for the North African campaign. As their work came to the notice of high command Clarke was summoned to London, in late September 1941, to brief the army establishment.

The Joint Planning Staff of the War Office were impressed with Clarke's presentation and recommended to the Chiefs of Staff Committee that a similar department should be formed in London to oversee deception across all theatres of war. Clarke was offered the job of heading this new section, named the London Controlling Section. However, he declined, preferring to return to Cairo.

Instead, on 9 October, the post was offered to Colonel Oliver Stanley, a former Secretary of State for War. However, Clarke had left very little information about 'A' Force and his own deception activities, so Stanley had to fend for himself. His task was made more difficult by the fact that strategic deception was a wholly new concept in England, and had few champions in the military establishment. The LCS was granted representatives from all three of the services, and theoretically had a lot of power. In practice there was little interest in deception. The army sent Lieutenant Colonel Fritz Lumby, while the RAF, refusing to send any Group Captains due to the Battle of Britain, commissioned the author Dennis Wheatley as their representative. This lack of interest left the LCS, according to Wheatley, in a state of "near impotence". The climate was not right for strategic deception on the Western Front, very few offensive operations were being planned, and Stanley was not able to do much to raise the profile of the department. However, the LCS did manage to put together Operation Hardboiled, a fictional threat against Norway, although it eventually fizzled out.

The end of Hardboiled was very demotivating. To make matters worse, Stanley's wife was diagnosed with a terminal illness, and he took extensive sick leave to care for her. In May 1942, Lumley was offered a posting to Africa, which he eagerly accepted. On 21 May two important events occurred; Lieutenant-Colonel John Bevan was selected to replace Lumley at the LCS, and Churchill received a letter from Archibald Wavell, the commander who had started Clarke's deception career in Cairo, recommending a broader Allied deception strategy. The letter seems to have invigorated Churchill's interest in deception; when Bevan arrived at the department on 1 June he found himself promoted to Controlling Officer; Stanley's request to return to politics having been speedily granted in the interim.

Bevan was a driven individual with good connections in the establishment. He recognised the role that the London Controlling Section could play in Allied strategy and set to work making it happen. Bevan kept Wheatley, another socialite, on the staff, and the two complemented each other well. He also recruited Major Ronald Wingate.