Curved Balance Beams on the Regents?
When the paired locks were side by side, on pair of balance beams were curved so that they fitted over the other, I recall that BW stopped doing this when they singled the locks ands as a cost-saving measure (the curved beams were much more expensive than the homogenised straight ones. I'm sure I've seen this in the Shepherd illustrations of the Regents... Ray Nb Owl [Non-text portions of this message have been removed]
