Reader - I finished it!!!!!
Well, it's almost Austen... the same sense of success, anyway.
Though I haven't blocked it yet, here is the finished shawl...
...and a close up of the lace edging,,,
...which is finished with Paton's Cotton Top, a yarn I think is now obsolete, in a fetching shade of biscuit. Nice, I think. (The biscuit, I mean).
I changed the instructions slightly, working an extra P row in the main colour, then doing one K row in the contrast and casting off loosely purlwise.