Throughout the summer, Cunningham and 604 had to sit idle and frustrated as the Battle of Britain raged.
By the autumn, the battle subsided.
Having failed to gain air superiority the Luftwaffe now resolved to bomb British ports and industries.
The change in German strategy began The Blitz phase of the aerial campaign.
On the night of the 19/20 November 1940 the Luftwaffe raided Birmingham.
The Germans hoped to follow up their attacks on the West Midlands after a highly effective raid against Coventry on 14 November 1940.
Pathfinders from Kampfgruppe 100 (Battle Group 100) led 369 aircraft from Kampfgeschwader 26 (KG 26—Bomber Wing 26), Kampfgeschwader 54 (KG 54), and Kampfgeschwader 55 (KG 55) to the city.

Cunningham took off this night from RAF Middle Wallop in Hampshire to patrol north of London.
When the direction of the raid was known he was ordered to proceed to the East Midlands.
GCI vectored Cunningham and his temporary radar operator John Phillipson—a former ground radar operator—onto an enemy aircraft, but the crew were forced much further westward.
Search lights attracted their attention and Phillipson was able to make a contact and guide him.
Soon visual confirmation was made.
A tell-tale sign of an aircraft was a blank patch of sky surrounded by a cluster of stars.
Keeping in the enemy's blind spot, he flew below it and adjusted his speed to match the German pilot.
After closing the range as much as he dared, he fired with all four cannons, downing the Junkers Ju 88, which exploded upon hitting the ground near Wittering, Cambridgeshire at 00:35.
Cunningham's victim, 3./KG 54 Ju 88 flown by Unteroffizier Kaspar Sondermeister, was not claimed as destroyed.
However, after interrogation of the two German survivors who affirmed the circumstances, Cunningham was granted the victory.

Cunningham had to wait a month for his next victory on 23 December 1940.
Kampfgeschwader 1 (KG 1) sent 100 bombers led by Kampfgruppe 100 to attack Manchester.
GCI vectored Cunningham onto the enemy aircraft.
It was not yet dark and Cunningham identified the machine as a Heinkel He 111.
Flying at 15,000 feet, he saw the Heinkel above the Beaufighter at 16,500 feet.
Cunningham engaged the enemy 50 miles south of West Lulworth.
The enemy climbed to 19,000 feet.
Following, Cunningham opened fire at 200–300 yards.
The He 111 was engulfed in fire.
The bomber was high enough for the crew to jettison the bombs and incendiaries and glide to France where it crash-landed at Cherbourg.
Two of Feldwebel Georg Deininger's crew were wounded.
The 3./KGr 100 machine was written off.
The crew were unaware they had been a victim of a night-fighter.
They supposed they had been shot down by a flak ship.

On 2 January 1941, Cunningham nearly added a third.
The Germans attacked Cardiff in the city's heaviest raid of the war.
Cunningham engaged an He 111 with an even spread of three aerial masts along its rear fuselage—indicative of a pathfinder.
He expended all the Beaufighter's ammunition against it from the working cannons—one cannon jammed.
It dived into clouds at 10,000 ft (3,000 m) at an angle of 50 degrees.
A 2./KGr 100 machine returned to France with a wounded gunner and Cunningham received credit for a probable victory.
On 12 January he claimed a damaged He 111—his first with operator Jimmy Rawnsley.
Cunningham was awarded the Distinguished Flying Cross (DFC) on 28 January 1941 for his achievements, including 25 night sorties.

On 9 February, upon the invitation of Charles Portal, Chief of the Air Staff and Sholto Douglas, Cunningham arrived at the Air Ministry.
He was ordered to report to Geoffrey de Havilland at Hatfield, though neither of the senior officers would say why.
When Cunningham met Geoffrey de Havilland he was summoned to a hangar.
It was the first time Cunningham had laid eyes on the de Havilland Mosquito.
Cunningham flew W4050—the prototype—on 9 February 1941.
He was greatly impressed by the "lightness of the controls and generally pleasant handling characteristics"; Cunningham concluded that when the type was fitted with AI equipment,
Throughout the summer, Cunningham and 604 had to sit idle and frustrated as the Battle of Britain raged. By the autumn, the battle subsided. Having failed to gain air superiority the Luftwaffe now resolved to bomb British ports and industries. The change in German strategy began The Blitz phase of the aerial campaign. On the night of the 19/20 November 1940 the Luftwaffe raided Birmingham. The Germans hoped to follow up their attacks on the West Midlands after a highly effective raid against Coventry on 14 November 1940. Pathfinders from Kampfgruppe 100 (Battle Group 100) led 369 aircraft from Kampfgeschwader 26 (KG 26—Bomber Wing 26), Kampfgeschwader 54 (KG 54), and Kampfgeschwader 55 (KG 55) to the city.
Cunningham took off this night from RAF Middle Wallop in Hampshire to patrol north of London. When the direction of the raid was known he was ordered to proceed to the East Midlands. GCI vectored Cunningham and his temporary radar operator John Phillipson—a former ground radar operator—onto an enemy aircraft, but the crew were forced much further westward. Search lights attracted their attention and Phillipson was able to make a contact and guide him. Soon visual confirmation was made. A tell-tale sign of an aircraft was a blank patch of sky surrounded by a cluster of stars. Keeping in the enemy's blind spot, he flew below it and adjusted his speed to match the German pilot. After closing the range as much as he dared, he fired with all four cannons, downing the Junkers Ju 88, which exploded upon hitting the ground near Wittering, Cambridgeshire at 00:35. Cunningham's victim, 3./KG 54 Ju 88 flown by Unteroffizier Kaspar Sondermeister, was not claimed as destroyed. However, after interrogation of the two German survivors who affirmed the circumstances, Cunningham was granted the victory.
Cunningham had to wait a month for his next victory on 23 December 1940. Kampfgeschwader 1 (KG 1) sent 100 bombers led by Kampfgruppe 100 to attack Manchester. GCI vectored Cunningham onto the enemy aircraft. It was not yet dark and Cunningham identified the machine as a Heinkel He 111. Flying at 15,000 feet, he saw the Heinkel above the Beaufighter at 16,500 feet. Cunningham engaged the enemy 50 miles south of West Lulworth. The enemy climbed to 19,000 feet. Following, Cunningham opened fire at 200–300 yards. The He 111 was engulfed in fire. The bomber was high enough for the crew to jettison the bombs and incendiaries and glide to France where it crash-landed at Cherbourg. Two of Feldwebel Georg Deininger's crew were wounded. The 3./KGr 100 machine was written off. The crew were unaware they had been a victim of a night-fighter. They supposed they had been shot down by a flak ship.
On 2 January 1941, Cunningham nearly added a third. The Germans attacked Cardiff in the city's heaviest raid of the war. Cunningham engaged an He 111 with an even spread of three aerial masts along its rear fuselage—indicative of a pathfinder. He expended all the Beaufighter's ammunition against it from the working cannons—one cannon jammed. It dived into clouds at 10,000 ft (3,000 m) at an angle of 50 degrees. A 2./KGr 100 machine returned to France with a wounded gunner and Cunningham received credit for a probable victory. On 12 January he claimed a damaged He 111—his first with operator Jimmy Rawnsley. Cunningham was awarded the Distinguished Flying Cross (DFC) on 28 January 1941 for his achievements, including 25 night sorties.
On 9 February, upon the invitation of Charles Portal, Chief of the Air Staff and Sholto Douglas, Cunningham arrived at the Air Ministry. He was ordered to report to Geoffrey de Havilland at Hatfield, though neither of the senior officers would say why. When Cunningham met Geoffrey de Havilland he was summoned to a hangar. It was the first time Cunningham had laid eyes on the de Havilland Mosquito. Cunningham flew W4050—the prototype—on 9 February 1941. He was greatly impressed by the "lightness of the controls and generally pleasant handling characteristics"; Cunningham concluded that when the type was fitted with AI equipment, 
John Cunningham (RAF officer)