Men meeting on a beach

Several summers ago, in north western Scotland, we were on Clashnessie beach. This being in Sutherland, there was no-one else there. We only went to this beach once that summer. We saw a man walking across the sand, looking very purposeful, not looking at us. My partner John said something like "that's David, what is he doing here?!" He then went across to him and chatted. It transpired that David used to work with John in Cambridge up until a year before, had then left that job and decided to walk around the whole of the coast of the British Isles, with girlfriend following in the "backup" vehicle - a VW campervan. John had been unaware of all this. David had that day been making his way around that particular bit of the Stoer penisular, north of Lochinver, during the few hours when we also happened to be there.