1) Always Tie in at both ends of the rope. (even when single pitch climbing). Most at the crag were not doing this as they had 60 or 60+M ropes. Ours was a 50M single rope which per guide book should be just long enough.
An overhand knot placed about 1 foot from the belayer's rope end would also work but is perhaps not the best method.
2) Belayer needs to always remain alert, inc observing the rope end and that sufficient rope remains. Debris ingress or a knot or kink in the rope end could also cause belayer problems which could be dangerous even if tied in at both ends etc. Belayers please occasionally check the rope end.
3) Buddy check should include everything, not just harness , rope correctly in belay plate, belay technique, should also include checking that the belayer has tied in or tied a knot on the rope end and that they know to regularly check the trailing rope. Dont assume they will do as discussed/presumed.
4) Experienced veteran climbers use their experience to check less experienced climbers more carefully and regularly.
5) Making presumptions can be dangerous.
Presumed belayer was experienced enough to know/remember/check this final tie in step and do it while I was preparing my gear to climb. Presumed belayer would regularly check for sufficient rope end and rope integrity while lowering. Tales of climbs in tough places do not guaranteed that mistakes can still happen !.
6)We did discuss and guide book checked that the rope length 50M would be just about enough if managed ok, but unfortunately got distracted from focusing on this point while lowering.
7) Incidents can be traumatic for the person who made the mistake. Take this into consideration. They too will be shocked. Everyone makes mistakes one time or another.
8) Risk Asses what could go wrong before starting to climb.
9)Always complete a post incident Incident report.