The tanks of the era were not reliable at all, slow, and were dangerous to their crews. It was a primitive and new technology; sure we now can complain and bitch in hindsight about the inability of the British commanders to use these "wonder weapons". But do we really expect them to do something intelligent with them if they were never used before? The British commanders did not have these things in 1913 to practice in peacetime so they can tailor the tactics to suit the strengths and avoid the weaknesses of the tank. Also the tank was every expensive and Britain couldn't afford too many. The war itself should have been contained to a Austrian-Serbian conflict. Austria was on her death bed anyways, it was only a matter of time.