I have to say that I never ever saw one but that's not to say they were not available of course. BUT, if they were available through Ordnance sores, then there WOULD be a B2/CR- XYZ type part number available too. And I never saw such a number (or item) in the old paper VAOS lists either.
On the other hand, we always had big piles of No4 type new and used scabbards available in order to use the scabbard button on No5/L1A1 scabbards where it'd broken off or was missing due to poor silver soldering. I seem to recall that the tinnies (the tinsmiths) would knock a few dozen off at a time and the turners would skim off the slightly rounded rear and they'd be ready to re-use on the No5's