Well, I assumed the lack of arrows meant it was bi-directional and got to work.
Feeling my way with a jewellers hammer though there seemed more give in a particular direction so I gently knocked both pins out from that side. They are indeed a pin and collar type arrangement similar to the older Omega bracelets and just as straightforward to change apart from the lack of directional guides.
After all that, I think I prefer it on the strap though it's growing on me!