I had forgotten that there was an interim uniform introduced in 1918 – that was absolutely hated by most RAF officers…

Just to clarify my comment above… I meant that the colour of the uniform was unpopular – the rank braid/lace looked pretty good with the bird and crown above it – I thought anyway : )
Of course the eventual and so far permanent RAF uniform colour (crabfat) was much less unpopular but I can understand the ww1 officers being reluctant to change from the Army colours that they had worn for some years previously !