When the 'K' model first entered RAF service, any of the sqn aircrew would go along as the 'trolley tart' (Cabin Supervisor) and look after the cabin. We had 2 ALMs (posted from 10 Sqn) to teach us the mysteries of things like General Declarations and Manifests, but they were never required as a mandatory part of the crew.
We also used the odd holding officer or two as CS, but there was no formal establishment for the VC10K Trolley Tart.
With the increasing 'Health and Safety' and other nanny-state regulations (which didn't allow 'untrained' personnel to pop an ACB into the oven for the stipulated time......far too difficult....
), the Cabin Supervisor empire was created and only those trained as such could now make the tea. Both 10 and 101 flew the VC10C1K (for which ALMs were scaled) as well as the few remaining Ks which hadn't been thrown away to keep the rest of the fleet staggering along. However, the ALMs then found a way of getting out of flying on UK AAR trips without passengers on the C1K - they would 'despatch' the aircraft and then slope off home. This consisted of counting the empty seats, doing the trim sheet and handing out the infernal S1 boxes - unlike the 101 Ops people of previous years, the 10 Sqn ALMs in 10/101 Ops weren't sufficiently competent to order real in-flight meals for what they ignorantly termed 'local' trips.... But those cross-trained as Trolley Tarts on the K were generally rather easier to work with than some of the old truckie fossils - and were very good at their jobs and a pleasure to have on board.
Of course when 101 took over 10, there were a load more ALMs and Air Stewards available, so finding a suitable Trolley Tart (of either, or indeterminate gender) can hardly be very difficult these days.