 It has been suggested that the pale blue colour was adopted as the cloth had been intended for use by the Imperial Russian Cavalry and, following their disbandment after the Bolshevik Revolution it became available at low cost.As it was the responsibility of officers to buy their own uniforms, a wearing-out period for old uniforms was allowed and the change-over to the air force uniform was slow.The 'wearing out' period also applied to other ranks.