Here is some interesting info on the "Battle of Britain"
It was RAF policy not to acknowledge top scorers, or officially use the term "ace" to describe a successful pilot worthy of the term. Fighter Command's tactics during the early war years were called "Fighting Area Tactics" which called for strict and disciplined formation flying. Individuality was anathema to this policy, so individuals were not singled out for praise and their achievements were not publicised, in order to discourage any undisciplined breach of standing policy by "glory-seekers". Also, it was felt - rightly - that to make too much of the fighter pilot's exploits would be to ignore the less-glamorous but just as vital work of Bomber, Coastal, Transport and Training Command pilots and crew. Returning pilots were debriefed and their claims totalled with an aim to assess total enemy losses, not to give them individual credit. However, Fighter Command could not prevent unofficial totalling of scores, especially when these led to award recommendations which became public knowledge when granted.
During the Battle of France word got out about a pilot who was scoring regular victories, and enterprising newsmen discovered his identity by these means. Pilot Officer EJ "Cobber" Kain DFC, a New Zealander and the first fighter pilot to receive the DFC in WWII, thus also became Britain's first widely-known ace of the war. Kain himself put the adulation down to his nationality, which he thought was being used to promote recruitment in the Dominions, and felt that another pilot, Flying Officer H "Fanny" Orton (who was shooting down even more enemy aircraft) should have been receiving all the attention. Kain was killed at the very end of the Battle of France. Various versions of the story of his demise exist, mainly about how he came to be in the air, with most claiming he was making a "farewell flight" and beating up the airfield and not actually on a combat mission. However, all versions agree that while he was performing low-level snap rolls, he stalled at 100 feet and crashed.
The official lack of recognition for "Aces" didn't stop newsmen from printing the following list in January 1941 of the top-scoring pilots, dating from the start of the war:
Sgt JH Lacey, DFM and Bar, 23.
PO ES Lock, DSO, DFC and Bar, 22.
Sgt HJM Hallowes, DFM and Bar, 21.
S/L AA McKellar, DSO, DFC and Bar, 20. Killed in Action.
S/L AG Malan, DSO, DFC and Bar, 18.
S/L RR Stanford-Tuck, DSO, DFC and Bar, 18.
F/O H Orton, DFC and Bar, 18.
P/O EJ Kain, DFC, 17. Killed in Action.
As to the best pilots of the Battle itself, all of the above except Orton (who was badly burned in France and was an instructor during the Battle) and of course Kain flew during the Battle. A notable omission from this list is Sgt J Frantisek. A Czech, he fled to Poland when his country was overrun. He joined the PAF, then when Poland fell, he went to France (via North Africa) and joined the Armee de l'Air, with whom he scored 11 victories and received the customary Croix de Guerre for his first air-to-air victory. He then went to England when France fell, joined the RAF, and although he was a Czech, was a founding member of 303 (Polish) Squadron, probably due to his Polish Air Force service.
Frantisek had absolutely no concept of discipline or teamwork - something which had held his career back from his days with the Czech Air Force. He would fly in formation with the squadron until the enemy was sighted, then would go his own way. His exasperated British Squadron Leader finally decided enough was enough; for all his results, such behaviour couldn't be tolerated. He offered to arrange for Frantisek to transfer to a Czech squadron, but Frantisek preferred to stay and fight alongside his Polish friends, with whom he had much in common. He was too good a pilot to be grounded, and all pilots were valuable, so a compromise was made. Frantisek was replaced in the Squadron formation, but allotted a "spare" aircraft so he could fly as a "guest" of the Squadron as and when - and how - he saw fit. Thus freed to fight his own private war, he would accompany the squadron on intercepts, but he would diengage almost immediately to fly a lone patrol over Kent, in the area through which he knew the German aircraft being intercepted would fly on their way back to base, possibly damaged and low on fuel and ammo. By this method, in the space of a month he downed 17 aircraft, of which 9 were Bf109s. He was awarded the DFM but otherwise received no official recognition for his exploits. He was killed when his aircraft crashed shortly after take-off on 8 October, cause unknown.
Contemporary research, including a thorough check of German records captured at war's end, has led to the revision of many pilot's credited victories. Even these are somewhat fluid. In his book Fighter Pilot, Paul Richey recounts a combat over France with some 15 Bf110s where 10 Zerstorers fell to his Flight of five Hurricanes, all of which were confirmed by French observers on the ground and by the physical evidence of their wreckage [see the scenario "Zerstorer Killers, 11 May 1940"]. Two were seen to lose their tails as they fell. Yet post-war German records show a loss of only 1 aircraft on this date by this unit, ZG26 - why they would show this is unknown, but clearly German records are not 100% reliable either. Another complicating factor is that wrecks of aircraft are still being discovered even today which can change a pilot's score. As an example, in WWI Eddie Rickenbacker shot down an aircraft on May 7, 1918, but this could not be confirmed at the time. Many decades later the wreckage was found, and this kill was credited to Rickenbacker on 20 January, 1960!
This is one listing I have found of likely victories during the Battle of Britain itself (i.e. not total victories) by Fighter Command pilots:
RANK PILOT A/C FLOWN KILLS
1 Sgt J Frantisek#, 303 Sqn Hurricane 17
2 PO ES Lock, 41 Sqn Spitfire 16 + 1/2
3 Sgt JH Lacey, 501 Sqn Hurricane 15 + 1/2
FO BJG Carbury, 603 Sqn Spitfire 15 +1/2
5 PO RFT Doe, 234 & 238 Sqns Spitfire/Hurricane 15
6 F/L PC Hughes#, 234 Sqn Spitfire 14 + 3 x 1/2
7 PO CF Gray, 54 Sqn Spitfire 14 + 2 x 1/2
8 F/L AA McKellar, 605 Sqn Hurricane 14 + 1/2
9 FO W Urbanowicz, 145 & 303 Sqns Hurricane 14
10 FO CR Davis#, 601 Sqn Hurricane 11 + 1/2
11 Sgt A McDowall, 602 Sqn Spitfire 11
Sgt RT Llewellyn, 213 Sqn Hurricane 11
# = Killed in Action during Battle.
If multiple pilots took part in shooting down an aircraft each was allotted a "1/2" kill.
As can be seen, aircraft type was no barrier to a good pilot, as the types are evenly represented on the list (note that Doe scored 13 of his 15 victories in a Spitfire). Nor was place of birth a barrier.
Two New Zealanders, a Pole, a Czech, an Australian and a South African-born American are on the above list, and the ratio of foreigners on the complete list of 104 Battle of Britain aces far outweighs the total ratio of non-British participants in the Battle. Rank was no hindrance either, with Sergeants and junior Officers prominent on the above list, even though the theory of Fighting Area Tactics gave the best shots to formation leaders!
