Escorts, not bombers.
Meeting Bf 109s at a) 22,000 feet, b) something above 20,000 feet, C) something well below 22,000 feet (lack of oxygen) and d) 20,000 feet is not unusual. It was the exact situation Park was keen to avoid when attacking large formations, if you read my post.
Nowhere did I say that the escorts were not stacked up above the bombers. On Battle of Britain day some of the escorts came in over Dungeness at 24,000 feet according to the Observer Corps. So what? They were not the principal targets.
Also on 15 September, Feldwebel Hermann Neuhoff from III./JG 53 wrote that his orders were to, "Assemble at 6,000 metres over Cap Gris Nez, where you will rendezvous with the bombers". The bombers crossed the Channel at 5,000 m, which is absolutely typical.
You won't find a large bomber formation approaching the English coast above 6,500 metres between July and October 1940. The VAST majority came across at about 5,000 metres
You seem to be under the impression that I think the Wildcat, as it existed in 1940, would have been useful to Fighter Command. It would not and if you read back you will see why I think that.