My jacket is making slow progress and I have now finished lining and quilting the jacket shell. I interfaced the entire jacket with Sheerweft since I could purchase it locally (thanks for all the suggestions). This worked well and the jacket seems to have kept its softness. Before quilting the lining I top-stitched both sides of each vertical seam to add strength to the loose fabric and help keep the seams lying flat inside the jacket.
I chose the bagged lining method suggested by Cheri Dowd in the Threads article, and attached the lining to the main jacket by stitching in the ditch along all vertical seams, then down the centre back and on either side of the centre front opening.
I was initially undecided about doing more quilting, mainly because I thought it may lead to disaster. However, I have a walking foot for my 201 Singer, purchased for this project, so I wanted to use it! Glad I did as the extra quilting seems to add shape to the jacket and (I think) it hangs better. Unfortunately I don't have before and after shots and perhaps the difference is too subtle to see in a photo (just a feel-good improvement).
The only hand sewing was the shoulder seams, back neck edge and a small section of the front neck edge. I had to snip the neck curves to turn under the seam and used fray check and many tiny hand stitches to help stabilise this (the loose weave seemed very fragile and I was pleased to have the interfacing). I sewed a line of top-stitching around the back neck as an added precaution, and when the trim is put this should provide a further layer of stitching, so I'm reasonably happy it will be ok. However, is there a better way to do the neck edge next time?
The cotton is a perfect match and the stitches seem to disappear inside the woven fabric and are not noticeable.
Now for the sleeves ...