[Skoshi Tiger]

There really wasn't anything that hasn't been said before.

Planes (at this stage) were close in performance - so close that success was more an issue of individual pilot skill than aircraft performance. If you use the stengths of your aircraft and exploit the weeknesses of your opponent you will have an advantage. The Germans always had a height advantage because they were the ones that initiated combat. The British were reacting to their raids and were climbing to meet them.

Spitfire +'s good manuverability and handling
easy to fly

-v'es negative G cutout
no cannons.

109 +'ves - no negative g cuttout
good dive speed

-'ves less manuverable
limited time in combat area

If we look at the cannon issue, The British did not have a mature weapon system developed in time for the Battle of Britain, simple as that. So they stuck with the proven system they had at the time (eight colt/brownings)

Why didn't the British go for a more proven cannon design like the German gun's?

Muzzle velocity. The Hispano Cannon had a initial velocity of about 880m/s compared to the german MG FF at 550-700m/s. The Hispano had a lot flatter trajectory and less time of flight.

Rate of fire. The Hispano at 750rpm fires a lot faster than the German MG FF at 540rpm.

Although the British didn't have a workable cannon for the Battle of Britian they ended up with a more effective 20mm aerial cannon for the rest of the war and after.

Cheers!