I think it was like that right at the beginning but, as the war went on and the officers were being killed in droves (in 1916 the average life expectancy of a subaltern on the Western Front was two weeks) the War Office had to turn to the rude mechanicals from north of Watford.
The Pals' battalions had their own officers from their own areas and it came as a bit of a shock to the top brass that men from the northern wastes made just as good officers as those from Public Schools who spoke nicely and knew which knife and fork to use.