Thanks both. I live in an area in close proximity to the Deliveroo base and another pizza delivery base and walk past both regularly so am quite familiar with what their groups of drivers look like and wear typically when they're waiting for jobs. This group struck me as different - it's hard to articulate exactly how their behaviour and clothing seemed different but, for example, the walk they took was around 5-10 minutes up the road and one wore just a balaclava (no helmet) the whole way - I would think most riders would have removed theirs. With luck you are right and it was just coincidental.