12 movements would do it but still a lot
Train arrives at Mallaig.
1. Loco uncouples, shunts forward.
2. Loco reverses along run-round line.
3. Loco comes forward onto observation car.
4. Uncouple obs from train, couple to loco, reverse to station throat.
5. Push obs forward onto turntable.
6. Uncouple, reverse loco clear.
7. Turn obs.
8. Loco comes forward again.
9. Couple up to obs and pull back from turntable.
10. Push obs forward into engine shed siding.
11. Uncouple, reverse loco clear.
12. Loco forward onto turntable.
13. Turn loco.
14. Loco forward off turntable.
15. Reverse onto obs in siding.
16. Couple up and pull obs forward to station throat.
17. Reverse pushing obs along run-round line to what will now be rear of train.
18. Uncouple, loco forward along run-round line to station throat.
19. Reverse back onto train.
20. Couple up, push train back onto obs.
21. Walk back and couple up obs.
22. Depart!!!
I bet the Fort William crews had some choice words about the Glasgow manager who "discovered" the old observation car.