1940
BOAC officially took over the operations of Imperial Airways and British Airways Limited on 1 April. The Secretary of State required BOAC to place the whole undertaking at his disposal.

May: The C Class Flying boats Caribou and Cabot were bombed and destroyed in Norway. BOAC Ensigns flew food to France for British troops cut off by German forces.

August: BOAC began a weekly 'Horseshoe' route from Durban to Sydney via Cairo and Karachi due to the direct route over Europe being cut. In October, the C Class Flying boat services linked Poole and Lagos in West Africa as part of the route across Central Africa to Durban.

1941
In February, BOAC started its special air service from Leuchars to Stockholm “the ball-bearing run,” using Lockheed 14s; from February 1943 unarmed Mosquito aircraft were used.

On 16 October BOAC assumed responsibility for the general administration of Air Transport Auxiliary. The ATA ceased to function as a ferry organisation on 30 November 1945 after delivering 308,567 aircraft of 147 types since 1940.

October: BOAC re-opened the UK-Cairo route via Lisbon, Gibraltar and Malta with C Class and Catalina flying boats.

BOAC’s first operation of the North Atlantic Return Ferry service took place on 24 September. The service, flown to the requirements of the RAF, used Consolidated Liberators; the first flight was made by Captain O.P. Jones. On 7 September 1944 BOAC completed its 1,000th crossing of the North Atlantic Return Ferry.

December: BOAC commenced irregular services across the North Atlantic with Boeing 314 flying boats G-AGBZ Bristol, G-AGCA Berwick and G-AGCB Bangor. These were continued throughout the war.

1942
Mr Winston Churchill MP, on 16/17 January, made the first transatlantic flight by a British Prime Minister – in BOAC Boeing 314 flying boat G-AGCA Berwick (Captain J C Kelly Rogers) from Bermuda to Plymouth.

February: Singapore fell to the Japanese in February and BOAC’s route to Singapore and Australia was terminated at Calcutta.

The G Class flying boats G-AFCI Golden Hind and G-AFCK Golden Horn were introduced on West African services.

October: BOAC made its first experimental flight from Prestwick to Ramenskoye (near Moscow) with a Liberator taking 13hours 9minutes for the flight.

Lord Brabazon of Tara chaired a committee to make recommendations for post-war development of civil aircraft. Among the recommendations were specifications for the Bristol Brabazon, the Vickers Viscount, the De Havilland Comet 1 and the De Havilland Dove.

1943
February: BOAC began a service over enemy-held Norway between Leuchars and Stockholm with de Havilland Mosquito fighter-bombers bringing back cargo of vital ball-bearings.

March: BOAC introduced Short S25 Sunderland III flying boats on the UK-West Africa route. The route was withdrawn on 25 October when the Sunderlands opened a UK-Cairo-Karachi service. Because of its operation through military areas, aircraft and crews were given military status.

May: Lord Knollys became Chairman of BOAC.

July: BOAC began a new Cairo-Wadi Halfa-Khartoum weekly service, with Lodestars. BOAC also introduced a five times per fortnight service by Ensigns between Cairo and Takoradi.

August: BOAC’s UK-Gibraltar service resumed, operated twice weekly with DC-3s.

BOAC UK-Moscow service via North Africa and Iran began flying converted Liberator bombers. During the first six months of the year BOAC made about 270 flights in the Western Desert. During the year it also introduced Douglas DC3 aircraft into service between the UK and Lisbon and Gibraltar and in North Africa.

1944
The first BOAC service commenced from Lyneham to Cairo, via Rabat and Tripoli, on 20 May, operated by Avro York G-AGJA Mildenhall.

June: BOAC rerouted its Cairo-Lydda-Habbaniyeh-Teheran Lodestar services to fly via Damascus and Baghdad to meet the Syrian government’s requirement for a Damascus-Baghdad connection.

September: BOAC completed the 1,000th crossing of the North Atlantic Return Ferry Service.

21 September: No 110 Wing, RAF Transport Command, began daily UK-Paris, Brussels and Lyons services. Subsequently, the Lyons service was extended to Marseilles and Naples and new services were begun to Athens, Prague, Warsaw, Copenhagen and Oslo.

November: Douglas DC3s were introduced on the Leuchars-Stockholm route and Mosquitos withdrawn.

1945
April: BOAC Lancastrian G-AGLF made a Hurn-Auckland proving flight, in a time of 60 hours. The first BOAC survey flight to South America was completed by Lancastrian aircraft G-AGMG Nicosia. A thrice-weekly Bermuda-Baltimore service by Boeing 314s was started and a Lancastrian service to Australia inaugurated.

On 1 November the new Labour government announced plans for post-war air services which would be provided by three state corporations: BOAC to continue to operate routes to the Empire, Far East and North America, British European Airways (BEA) to operate services to Europe and domestically within the United Kingdom and British South American Airways (BSAA) to operate new services to South American and Caribbean destinations.

A joint BOAC and South African Airways Springbok service was inaugurated on 10 November, using Avro York G-AGNT Mandalay; route was Hurn-Castel Benito-Cairo-Khartoum-Nairobi-Johannesburg.

1946
January: Wartime restrictions on flying ended.

February: BOAC Hythe flying boat G-AGJM Hythe made a 35,313 mile route survey from Poole to Australia, New Zealand, Hong Kong, Shanghai and Tokyo.

15 March: British South American Airways began a regular service from London to Buenos Aires via Lisbon, Bathurst, Natal, Rio de Janeiro and Montevideo using Avro Lancastrians.

12 May: The first post-war UK-Australia flying boat service operated jointly by BOAC and Qantas with Hythe flying boats commenced, taking five and a quarter days.

Heathrow officially opened on 31 May as the new London Airport to replace the old Croydon grass airfield. BSAA had operated the first international departure from there on 1 January when Avro Lancastrian “Star Light” – a converted Lancaster bomber – carrying 13 staff passengers left on a proving flight to Buenos Aires.

BOAC operated its first departure from London Airport, on 28 May, instead of Hurn. The flight, by Lancastrian G-AGLS Nelson, was to Sydney, a 63hr journey.

On 1 July BOAC opened London-Shannon-Gander-New York flights by Lockheed Constellations, the first British civil flights on the North Atlantic. The first flight was operated by G-AHEJ Bristol II (Captain O.P. Jones). A new era was heralded in with new pressurised aircraft that could fly over the weather such as the Canadair Argonaut, Handley Page Hermes and Boeing Stratocruiser.

On 1 August British European Airways Corporation (BEA) took over the services operated by the British European Airways Division of BOAC operating shorthaul routes from Northolt. BEA operated the unpressurised Douglas DC-3 and the Vickers Viking developing a large flying programme that for several years made Northolt one of the busiest airports in the world.
BOAC began services to Hong Kong with Hythe flying boats (Dragon service) and return fares were introduced on all BOAC routes.

September: The first scheduled BEA Viking 1A service London to Copenhagen operated on 1 September (G-AHOP Valerie). On 2 September BSAA began fortnightly London-Azores-Bermuda-Jamaica-Caracas, first flight by Lancastrian G-AGWL Star Guide (Captain Gordon Store). On 30 September the G Class flying boat G-AFCI Golden Hind began the first commercial service between Poole and Cairo.

1947
12 March: The Durban-Calcutta Horseshoe route was closed and C Class flying boats withdrawn from service.

15 April: The first commercial BOAC operation to Canada commenced with a weekly Constellation service between London and Montreal, via Prestwick and Gander. This was BOAC’s first commercial operation to Canada; the first three services operated via Shannon and the first via Prestwick was on 6 May.

2 May: BOAC introduced Plymouth class Sandringham flying boats into service on the Poole-Bahrain-Karachi route.

1 July: Sir Harold Hartley was appointed Chairman of BOAC.

1 July: A twice-weekly London-Karachi service commenced using Handley Page Halton aircraft, replacing the charter service operated by Skyways.

14 July: BOAC began UK-Ceylon services, via Tripoli, Cairo, Basra and Karachi using Handley Page Halton aircraft.

1 August: The UK, Australian and New Zealand governments agreed to form British Commonwealth Pacific Airlines.

10 August: First all-freight scheduled service, London-Brussels-Prague on a daily frequency, commenced and a weekly London-Tehran Douglas DC3 service.

September: A Trans-Sahara London-Lagos service commenced.

December: The first all-cargo flight London-Sydney Lancastrian service commenced.

BSAA introduced the Avro Tudor, its first pressurised aircraft, in late 1947.

1948
January: The last BOAC Boeing 314 flying boat was withdrawn from service and Darrell’s Island marine base at Bermuda was closed. The final flight was by G-AGBZ Bristol.

February: Start of London-Nairobi York service by Avro York aircraft.

19 March: BOAC’s Plymouth flying boats extended Britain-Hong Kong service to Iwakuni, Japan and to Tokyo in November.

31 March: BOAC flying boat base transferred from Poole to Southampton Water.

11 April: Start of weekly London-Johannesburg cargo service by Lancastrians.

4 May: BOAC introduced Short Solent flying boats introduced on UK-Johannesburg service. The route was Southampton-Augusta-Cairo-Luxor-Khartoum-Port Bell-Victoria Falls-Vaaldam. First flight by G-AHIT Severn.

31 May: BEA opened Dorland Hall and Kensington Air Station.

The Berlin Airlift started on 27 July; BEA co-ordinated the civil airlines’ operations. BSAA aircraft also took part. The Airlift finished on 15 August 1949.

In October, BOAC provided air ferries between India and Pakistan after the partition of India, carrying some 43,500 civilians.

December: Start of once-weekly London-Sydney service by Lockheed Constellation aircraft. The first flight was by G-ALAL Banbury (Captain G.R.Buxton)

1949
BSAA had suffered the loss of a Tudor aircraft in January 1948; following the loss of a second in January 1949, the type was grounded. On 30 July, BSAA was merged with BOAC.

15 February: Last Hythe flying boat services. BOAC Sunderland and Hythe flying boats flew 25,111,246 miles and carried 79,793 passengers.

March: First Canadair Argonaut airliner delivered to BOAC.

14 March: Lord Douglas of Kirtleside appointed Chairman of BEA in succession to Mr G d’Erlanger.

29 May: £10 night excursion fare to Paris introduced.

1 July: Sir Miles Thomas succeeded Sir Harold Hartley as BOAC’s Chairman.

23 August: First all–land plane service by Canadair Argonauts on London-Hong Kong route, via Rome, Cairo, Basra, Karachi, Calcutta, Rangoon and Bangkok. The first flight was operated by G-ALHJ Arcturus.

BOAC operated its first London-New York Stratocruiser service (G-ALSA Cathay) on 7 December. First flight by G-ALSA Cathay; flight routed via Prestwick with a schedule of 19hrs 45mins.