Hi Gents, some help please... My Grandfather enlisted in the Royal Navy in 1915 then to the RNAS as a Rigger (Airship)and I have his Royal Navy Certificate of Service his service number is F10***. In April 1918 he was transferred to the RAF still as a Rigger (Airship) and I have his RAF Certificate of Service, his service number is now 210***. In September 1918 he was discharged from the RAF as he was selected for a temporary Commission as a Sub Lieutenant in the RNVR. I have his medals marked with his RNVR rank and I have his RNVR commission document. What I'm after is his new service number as an Officer in the RNVR any ideas where I could find that out ? Would he have kept his RAF number ? reverted back to his RN OR's number ? Thanks.