RAF regulations said that the eight Brownings should be adjusted so that the bullets converged at a point some 650 yards ahead of the aircraft. As one pilot of 54 Squadron said at the time, "All this guarantees is a few hits by the indifferent shot; the good shot on the other hand is penalized." The pilots who were prepared to get close were scattering gunfire all over the place.

Already the regulations were being ignored. Armament Officers were having the guns adjusted the way the pilots wanted them (and eventually this was officially approved).

The courage to fly very close distinguished just about all the men who became aces, but without the skill of deflection-shooting such a pilot could not make a kill. This aiming-off is not to be equated with the hunter shooting at a bird in flight. The fighter pilots were moving at three or four hundred miles an hour in three dimensions. And so was the target. To hit it required an instant assessment of enemy speed, enemy size, angle between the two aircraft, and the distance. (Later in the war there were gun-sights that did some of this calculation, but in 1940 pilots on both sides had only a ring sight reflected on the windscreen.) The split-second judgment required for this kind of fighting was something that many superb pilots were never able to acquire.

In the First World War, some ace fighter pilots had become obsessional about the types of bullet they used, arranging them in the belts in certain set sequences according to personal taste. The provision of eight separate identical guns made varying the ammunition very simple. A common mix was four guns with normal bullets, two with armour-piercing, and two with the new De Wilde incendiaries. This later ammunition was very popular with the fighter pilots. Dowding said that they valued it far beyond its true worth but he was not taking into account the way that, although it had no tracer or smoke trail as previous incendiary bullets had, it made a bright yellow flash on impact. This proved a valuable aiming device. Believing that his pilots should have what they wanted, Dowding made special efforts to increase supplies of the De Wilde bullets. 'Sailor' Malan and Al Deere believed that the 250-yard harmonization and De Wilde bullets made the difference between damaging enemy aircraft and destroying them.

During July the fighter pilots rediscovered that aerial victory went to the formation that caught an enemy unaware. The old hands attacked out of the sun, and visibility was the paramount factor in the fighter pilot's war. German pilots who had found their Emils good enough for Spain, Poland, and France, now demanded a better clear view cockpit cover. RAF pilots were constrained by their Irving flying suits, gloves, and the seat's Sutton harness which, one inspector said, "seemed specially designed to foul oxygen and wireless leads." The RAF flying helmets had earphones that tangled into the collar part of the 'Mae West' life jackets. To relieve themselves of this tangle many pilots adjusted the cockpit heaters and flew in uniform jackets or shirt-sleeves.

But for the ground staff there were few days suitable for shirt-sleeves. July was a month of dull, wet weather: haze, drizzle, low cloud, electrical storms, and even fog. Often it was the appalling visibility that enabled a convoy to get through the Channel intact. There was so much rain that some airfields on both sides were made unusable by flooding.

And then 25 July provided one of the rare breaks in the bad weather: the morning sky was blue.

Kesselring was playing cat and mouse with a convoy through the Dover Straits. CW8 (west-bound coal convoy number eight) consisted of 21 colliers and coasters. Only 11 passed Dungeness, and only 2 got to their destination undamaged. Just after noon, a force of Bf 109s headed for Dover, flying almost at sea level. They were a device to bring the RAF fighters down to sea level and so give a clear run to the Stukas. No. 65 Squadron went down to fight. All the aircraft were so low that when one Bf 109 of JG 52 misjudged an attack, he hit the water and disintegrated.

Hurricanes of 32 Squadron from Biggin Hill and 615 Squadron from Kenley joined the fighting against forty Bf 109s. There is an old fighter pilot's maxim, "Never throttle back in combat," and maximum boost caused both sides to run low on fuel after only a few minutes. As the fighters disengaged, three Stukageschwader came in at medium altitude and dive-bombed the now-unprotected convoy.

The convoy's naval escort put up anti-aircraft fire and called urgently for fighter cover. Nine Spitfires of 54 Squadron hurried to their aid. When they arrived they found Kesselring had sent an overwhelming force of Bf 109s there to wait for them. Among 54 Squadron's losses was a flight commander. None of the German fighters was shot down.

The Sector Controller realized that if he answered the German attacks plane for plane, he would be bled dry. So at 2:30 that afternoon, when thirty Ju 88s came to bomb the convoy, he sent only eight Spitfires of 64 Squadron. They met a fighter escort of fifty Bf 109s. Undismayed, the newly appointed squadron commander called "Tally-Ho!" and attacked. The Controller sent the rest of 64 Squadron three Spitfires and 111 Squadron, to the battle. The latter formed up line-abreast and did a head-on attack on the Junkers bombers, which broke formation and turned away. On seeing this, the Messerschmitts of the fighter escort also withdrew.

But it was still only afternoon: the men of the convoy had not yet earned their day's pay. As they passed Folkestone, the Bf 109s repeatedly strafed them at sea level, gaining the naval gunners' attention so that about sixty Stukas could dive-bomb them out of the afternoon sun. The attack had been nicely timed between RAF patrols, and with unhurried precision they sank five ships and damaged four. At this moment, a force of German motor torpedo boats attacked the convoy too. By nightfall two damaged destroyers moved into Dover harbour; one of them was under tow. The Admiralty concluded that coastal convoys should no longer try to get through the Straits of Dover except under cover of darkness.

Although Fighter Command had lost only seven aircraft against sixteen German raiders shot down it had nothing to celebrate. No. 54 Squadron was retired north for a rest. In its three weeks in action the Squadron had lost five pilots killed — including a very experienced flight commander — and three pilots wounded. It had flown 800 hours, completed 504 combat sorties, and lost twelve aircraft. It was a warning of what could happen to the whole of Fighter Command if it was drawn into ever larger battles. Instead of cancelling the coastal convoys — the cargoes were coal, which could have been moved by rail and later was — the Admiralty and Air Ministry pressed Dowding to commit more of his fighter force to protecting the shipping. Dowding resisted.

The US ambassador in London Joseph Kennedy, the father of the man who became President, had little faith in Britain's ability to survive, and he didn't mind who knew it. As early as 1 July the British Prime Minister had written in his diary, "Saw Joe Kennedy who says everyone in USA thinks we shall be beaten before the end of the month." Now there was only a week of it left. The British Foreign Office heard that Kennedy had summoned neutral journalists to a press conference in order to tell them that Hitler would be in London by 15 August. Such behaviour infuriated Foreign Office officials — one wrote, "He is the biggest Fifth Columnist in the country" — but there was little they could do about him. Joseph Kennedy wielded great political influence in the USA (and had got the London Embassy in recognition of past help). Now it was election year in the USA. President Roosevelt was running against Wendell Willkie for an unprecedented third term. He needed Kennedy's support to win the election, and the British wanted Roosevelt to win. It was a dilemma for all concerned, not least for the Americans, who didn't want to send expensive war supplies to a nation just about to collapse.