After feeling around a bit between the inside door skin and the window glass, and thinking it through, i decided I needed to drill some small holes in the inner door skin (under the trim and in a couple of the reinforcing recesses) and put a loop through to hold the rod close to the inner door skin and away from the window mechanism. I used a couple of mini plastic cable ties (really small black ones i use in desktop pc's to secure wires) and looped them through 2 holes each, around the rod and back out again, tied on the outside of the inner skin in the recess. I found the control rod had a hand-sewn cloth cover on it that i later worked out was for sound deadening (clatter on the window or door) and I removed that so that the plastic ties would slide freely on the metal rod and not snag on the material. To reinstate the sound deadening I put a strip of 50mm cloth tape on the inside of the inner skin running parallel to the rod.
Put it all back together and now I have a lockable door, window up or down. The car will be called into service for my daughter's wedding in April so I will need to be able to lock and leave it secure.
Also this weekend fitted a NOS pair of Marchal 7 inch headlights from Europe and new halogen globes from classic and vintage bulbs in Adelaide. Another minor drama, the six little fixing and adjustment screws on the existing headlights (3 each side) did not fit the new lights ( in spite of careful ordering) so I had to rob them off my 65 car and will have to get replacements. No matter how careful we are with checking and ordering parts there are so many minor variations (dozens of different 7inch ts in this period for example) just waiting to trip us up.