Mike,
Bit more research has shown that Thetford, as quoted above, was wrong. R.33 seems to have been demilitarised in 1920, although still used for RAF related trials such as:
AEROPLANE LAUNCHED FROM THE AIR - British Pathé
However, R.34 appears to never have been civillianised, and was operated by the Air Ministry for some of the time before her demise in 1921.
As Milo quotes above:
The Admiralty agreed to lend their airships to the Air Ministry for long-distance trials.
So Admiralty owned, Air Ministry operated. Does that count as RAF? Might be best called a draw!!
Airshipsonline : Airships : R34
(and of course her captain was Major G H Scott A.F.C)