Not really. The fighter bases closest to France, and their squadrons, were taking a hammering at one point but there were many fresh squadrons a bit further away which could have been rotated in if necessary. If all else failed, the RAF could have abandoned the closest bases and carried on fighting from airfields beyond Bf 109 range. But the RAF fighters would still have been within easy reach of London - and the beaches.

The BoB actually hurt the Luftwaffe more than the RAF - they were failing to make up their losses in men and planes, whereas the RAF was more or less as strong at the end of the BoB as it was at the beginning.

And the longer the Germans delayed before the invasion, the more time the British had to strengthen their defences and replace the army equipment lost at Dunkirk.

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Tony Williams: Military gun and ammunition website