The British Royal Air Force Ensign is in light 'Air Force' blue with the Union Jack in the canton and the Royal Air Force roundel, concentric rings of red-white-blue (from the inside out) in the middle of the fly. Before 1918, the Royal Naval Air Service used the White Ensign. An interim flag was produced to represent the Royal Air Force at the armistice celebrations; a 'white ensign' with an overall dark blue St George's Cross, the Royal Air Force eagle in the centre of the cross, and a royal crown above it on the vertical arm of the cross. Rather more attractive than the roundel ensign, but not to the liking of the Admiralty who thought it looked too much like a naval flag. Between the armistice and 26 July 1920 when the present ensign was approved, the Royal Air Force was supposed to fly the Union Jack, but some former Royal Naval Air Service units flew the White Ensign, or the white ensign with a blue St George's cross, but without the eagle and the crown. The RAF have always referred to their flag as the RAF Ensign. It may possibly be an analogy with the White Ensign, particularly as the RAF originally wanted to have a White Ensign without the cross as their flag (they also tried a White Ensign with a blue cross which they referred to as a St Michael's cross). The Admiralty, on the other hand, stubbornly referred to it as an RAF flag, refusing to admit that the RAF had any right to fly an ensign.