WS19 MK II unusual control box plus decal

[Patrick Johnson]

The Canadian War Museum collections site produced the following photos which I find interesting on a number of accounts. It is an early Mk.II produced by Northern Electric and has an unusual decal where the watch holder is normally located. But more interesting from a Control Unit standpoint, what function does the box mounted on the viewer's left serve? And where do the leads at the bottom go? Hopefully someone will have some idea as I've never seen this variation before. The photos of this unit are found here:
http://www.warmuseum.ca/collections/...ia_irn=5389446
Cheers, Patrick