Two of the greatest problems of the British Army are, 1) Deliberate amateurism. A friend of mine was pulling a night shift in a NATO exercise and a British major of Engineers said, "Andy would you post this for me? I don't read coordinates." !!!!
The second is failure to communicate. At Singapore, the first Japanese troops crossing the Straits of Johore were badly shot up -- but Lieutenant General Perceval assumed from the shooting that he had been defeated again -- and didn't get any reports telling him differently. He ordered a withdrawal to the Jurong line, and most unit commanders had no idea where the Jurong line was, or what their position in that line was supposed to be. And his staff failed to point out that all of his ammo and supply dumps were NORTH of the Jurong line, so he effectively gave it all to the Japanese.
Disasters like Gandamak, Isandlwana and Spion Kop all trace back to those two problems.