After all the earlier interesting discussion on these "trials type" guns I followed up with the dealer and managed to secure the last one.
From the features and markings I believe that it's one of those ordered by the Irish Army in 1936/7. I think the story goes that the Irish placed an order with Britain. Enfield, having their hands full with development of "their" Bren, in turn ordered these from the Czechs. The Czechs apparently took this to be an order for the last agreed prototype but when it turned out not to be to the latest design the balance of the order was cancelled after only 2-300 guns had been produced. These early guns were consigned to DP status by the Irish as they acquired Mk3 guns in the 50's.
I've tried to show some of the salient features of this example - FF Irish marking, AA sight mounting point/ring on the butt, different tripod mount on the butt, forward sling mount, etc.
On initial inspection I think the only non-original part is the Enfield marked bipod. In actual fact this is not the gun I was expecting to receive - the pictures of the one I ordered had an Enfield type butt with the British rather than Czech tripod mounting point but what was interesting on that example was that it also had the AA sight mounting ring at the front of the butt - it had a slightly later serial number so maybe the Brno factory updated the specs as the order progressed? Anyway if this is one of only 2-300 or so guns to this spec I'm happy to add it to my small collection.
Apologies for the iphone pictures - these were taken in haste as I had to head away for a work trip and as a consequence I've not had a chance to check the internals yet. Luckily however it is not to the latest EU "only any good as a paperweight" deact spec, so it still cocks, dry fires etc.
Hope this of interest.
Kev