Two days on and some more to report. First off, sadly that jig didn't work anything like as well as I expected. It was very diffciult to get the vertical bars truly vertical as can be seen from the two on the right here:
At this point I was on the very of calling it a day and giving up, however I had one more idea on how to drill the bars so the holes lined up better and so created another, smaller - in fact tiny jig that supports the bar pieces and lets me measure the space between two holes and then gives me a good alignment to drill the next hole. This does mean that I've given up on trying to drill whole sequences of holes and switched back to one at a time. IT may take a bit longer but it is more accurate and in the long run faster as I make fewer mistakes and don't have to keep rebuilding pieces .As it stands, the two on the right in the above photo are not fit for anything except the spares/scrap box.
The good news is that since I started using the new jigs, progress has accelerated so that now I have these pieces all done...
The two pieces in lower left and lower right are in the process of having their holes drilled for the brass rod, but its nice to have finally got some good, even looking pieces so it has given me much encouragement to continue and return to the larger pieces.
Now in the meantime I've been checking more photos of the bar armour in situ. Checking the Concord "British Army Battle Group" and the Tankograd Task Force Helmand, has made me realise that the plans I had before are still wrong... the front and rear plates are too narrow and also the wrong configuration. On the hull rear, there are three sets of 2 "column" bar armour, plus single columns either side, to make a total of 8 columns width. The hull front and turret rear has a single 6 column panel flanked by 2 singles. In my earlier drawing I had them all 6 columns wide in total. Thankfully, that doesn't make a difference to me yet as I haven't built that far.
Its off I feel like I make a bit of progress, then get bogged down and stuck for a while, then make another small sprint forward! This time I feel much more positive and am enthused about moving forward!