After a reply from a gent who knows much more about the real thing than I do, my life was made easier when he said that the smaller pipe didn’t actually feed into the down vacuum pipe put was clipped to the back of it. This saved another delicate 0.4mm drilling job.

It’s not exactly clipped but it’s out of sight behind the vacuum pipe when fitted so well hidden.

The observant amongst you will note, that the small pipe at the smokbox end was a casualty of my ministrations. So that will need reattaching.

Also, since the photos were taken I have shortened the union at the rear of the vacuum ejector which holds the pipe that goes into the cab. It’s now more ‘nut’ like… Plus I’ve cleaned up much of the excess solder even though it’s out of sight.