There was to be a Recce Regiment in the Pentropic division, but that was never fully formed. In any case this Regiment was supposed to have one sqn with the Armoured Regiment and the other 2 with the Combat Support Group. I've been focused on the 2 sqns in the CSG, there were just enough Saladins and Saracens to form that part of the unit. I suppose the sqn in 1AR could be just as valid, indeed it could have a 'heavier' composition with more Saladins and Saracens than the standard Pentropic sqn structure.
As for why this unit was never formed, I think by the time we got enough M113s to form units it was realised we would never form a Division, so the Cavalry Regiments were half Recce and half APC for Brigade work.