One thing I couldn't understand is why the first runway built was never actually used and the authorities seemed to be aware of the fact it wasn't needed but still spent £400,000 on it in 1944. This was the 'central' NW/SE aligned runway (15/33?) and would now be known as 15C/33C and now lies under the central terminal area.
I think that runway shows up on an old map from 1948 I found on Wiki.
There is also some interesting information on the history of the area on this page: