Unusual dual locking double 'layered' pipe key lock

[Huw Eastwood]

Here's one found recently that's really got me scratching my head.
I think it's one we possibly swapped through the MLA many years ago, but i am guessing as it's from that long ago now.

All looks very non-descript and normal when viewed from the front, but removing the cap reveals there's two layers to the lock- the top 4 lever section simply acts as a shutter and retracts to fully uncover the secondary keyhole underneath.

The lower lock is also 4-lever but has additional false gates and directly retracts the bolt bar of whatever it was used to lock.
Unfortunately the top section was drilled at some point and there's damage to the top lever pack, but its so unusual to make me think it's worth my time re-instating all the levers and making two nice repro keys using antique period blanks. I'm also convinced there's parts missing from the top left area of the lower lock, seen in the last photo.

Intricate hand fabrication work, machining, brazing etc, and hand making such keys have always been my forte, so any information would be greatfully received as I'm actually pretty eager to make a start on it! Well, that's if it's unusual/rare enough and all worthwhile doing of course!