A number of months after they enlarged every single fighter field in the UK???
or perhaps just a fair number of them.
All those British mid 30s fighters had to operate from small airfields using crap propellers and primitive flaps.
fastest fighter in the world doesn't do much good if it can't take off and land from most of the air bases in country.
Speed is an easy to measure metric. Take the Hurricane (say 320mph) and the Spitfire (say 360mph) and now put the Hurricane into a turn where it is doing 290 mph (gentile turn) and can just maintain altitude. Now have the Spitfire do the same radius, speed and bank angle. The Spitfire has the option of climbing while turning, the Hurricane does not. The extra 40mph represents surplus power that can be used for maneuver if the planes are flying at near the same speed, even if it is not near top speed.
Completely agree with the crap props, but not so about the flaps. In single-seat fighters of the day there was not much other option than hinging a flat plate under the wing. No other front-line single-seat fighter had any different. But those big wooden clubs on the front of Spitfires and Hurricanes into early 1940???
As for the Hurricane's speed, like wot's been said lotsa times, you go to war with what you've got and the Hurricane, thanks to pre-war orders was the most numerous fighter in RAF service. Its lack of speed compared to the Bf 109 was known about at the time. Did any Hurricane pilot ever feel that it was a disadvantage to their ability to tackle the enemy on equal terms? I've certainly not read anything suggesting it.
Let's not forget while we are debating that the Hurricane was 'inferior' because it was slower than the Bf 109, that the RAF was trying to stop bombers, not fighters. According to statistics, Bf 109s shot down more Hurricanes and Spitfires than Hurricanes and Spitfires shot down Bf 109s, yet Fighter Command shot down more Luftwaffe aircraft than the Luftwaffe shot down Fighter Command aircraft. That's what mattered.
It's interesting to note that it is a Hurricane squadron that recorded the RAF's highest kill-to-loss ratio during the Battle of Britain, 303 Sqn at 14 to 1.