I have seen triangles both ways. Digby which is authentic and Duxford have inward pointing. The original ops room clocks have outward pointing. They changed before the war. At least that’s what my neighbour said who is a guide at Digby.
My own clock has far too many triangles. Cheap Chinese copy available from aviation retailers such as Pooleys and various museum shops. £19 is far better than £8,500 for the real thing.