163rd (Mixed) Heavy Anti-Aircraft Regiment was an air defence unit of Britain's Royal Artillery formed during World War II.

By 1941, after two years of war Anti-Aircraft Command, tasked with defending the UK against air attack, was suffering a manpower shortage.

In April its commander-in-chief, Lieutenant-General Sir Frederick 'Tim' Pile, proposed to overcome this by utilising the women of the Auxiliary Territorial Service (ATS).

The ATS was by law a non-combatant service, but it was decided that Defence Regulations permitted the employment of women in anti-aircraft (AA) roles other than actually firing the guns.

They worked the radar and plotting instruments, range-finders and predictors, ran command posts and communications, and carried out many other duties.

Although much damage was caused in London, the rising efficiency of the HAA guns and radar made the enemy's losses unsustainable.

Defences had been planned against this new form of attack (Operation Diver), but it presented a severe problem for AA guns, and after two weeks' experience AA Command carried out a major reorganisation, stripping guns from the London IAZ and other parts of the UK and repositioning them along the South Coast to target V-1s coming in over the English Channel, where a 'downed' V-1 would cause no damage.

[1][9][17] By now, AA Command was being forced to release personnel, both male and ATS, for service with 21st Army Group fighting in North West Europe, and a large number of units had to be disbanded.

It was replaced on 7 February 1945 when 505 (M) Bty joined from 157th HAA Rgt, but by then the war in Europe was coming to an end.

It was reduced to a cadre in London on 30 June 1948, 323 Bty was disbanded on 10 October, and RHQ and the other two batteries were placed in suspended animation on 10 November, completing the process by the end of the month.