On 7 June 1946, BBC Television resumed broadcasting. On 1 September 1939, two days before Great Britain entered the Second World War, broadcasts were stopped without warning. The Air Defence Command and the British Air Force feared that the VHF signal could become a radio beacon for German bombers. Most of the company's technical staff and engineers were mobilised into the Army to work with radars for London’s air defence system.

The last programme to air in 1939 was Walt Disney's cartoon "Mickey's Gala Premiere" about Mickey Mouse.  

The BBC Television Service began regular broadcasts in 1936, although experimental programmes had been in production since 30 September 1929, when John Logie Baird broadcast the first programme by his Baird Television Development Company via a BBC transmitter. Simultaneous transmission of sound and image was achieved by 30 March 1930.  Since 22 August 1932, the BBC began airing its own television programmes.

On 2 November 1936, the BBC Television Service began broadcasting from a wing of the Alexandra Palace in London converted into a studio. The “Ally Pally” housed two broadcasting pavilions, set design workshop, makeup rooms, offices and control rooms.

The BBC became the world's first regular high-definition television service; it aired the news from Monday to Saturday from 15:00 to 16:00 and from 21:00 to 22:00. The first programme broadcast on a special TV channel was "Opening of the BBC Television Service" at 15:00. The first external broadcast was the coronation of King George VI and Queen Elizabeth in May 1937. Television was becoming more and more popular, and from 1936 to 1939, 18,999 television sets were made in Great Britain.

On 7 June 1946 at 15:00, Jasmine Bligh, a presenter, appeared on people’s screens with the words: “Good afternoon. Do you remember me? I am Jasmine Bligh. We were interrupted.” And the very same cartoon, which was being shown when the broadcast ended in September 1939, was aired.  

Source:

BBC official website https://www.bbc.com/historyofthebbc/100-voices/birth-of-tv/ally-pally