The idea
Excavate a trench to bearing depth, then fill it almost to ground level with mass concrete. No formwork, no separate footings — a continuous concrete strip the wall sits straight on top of.
Why it is popular
Faster than strip-and-block, less labour, fewer chances to get the build-up wrong. On clay sites with trees nearby, the deeper trench often makes engineering sense anyway.
Where it goes wrong
Trenches collapsing in soft ground, water ingress before pour, concrete poured to the wrong level, and bearing depth not actually achieved. Inspect before pouring, not after.