No Hard Runways
Prior to WW2 Aerodromes were essentially grass and aircraft operated into wind as the norm, with aircraft performance and the ability to fly on one engine not the safety issues as of now.
The pre war machines tended to have fixed UC and large wheels as this suited the natural surface available, so no one was really used to 'runways' as we know them now. When the metal monoplane became the standard design of most aircraft, the wing loading and weight coupled with smaller wheels made grass an unreliable surface due to its loss of bearing strength when wet. The RAF realised this during the expansion period and could see that it was no good having a modern fighter force that could easily be grounded by the local weather conditions, so the classic 3 runway airfield became the new standard for them. Many of the pre war civil municipal 'Airports' were never converted to this standard and Croydon was one of them. It seems ludicrous now that when Vickers test flew the Valiant prototype they did so from the still waterlogged grass surface at Wisley and he aircraft ruined the surface with huge ruts. Gatwick was well know for being prone to surface problems but the thinking of the day was INTO WIND not why is this not working. Croydons original advantage was its links to London and being closer to the popular destination of the time Paris. In fact Croydon pioneered many of the Air Traffic rues that became the norm and its terminal was a model of what we know would call passenger transit. Croydon was always surrounded on three sides by built up area's so it could never expand its directions to cater for increased performance regulations, and the Government wanted the Civil trade to go to the improving Gatwick anyway. It played its part in the Battle of Britain when needed, so all in all it did its bit for us in two conflicts, and also pioneered Civil Aviation in this country. Gets my vote.