It did not turn out that way. The varnish had runs and wrinkles, and did not have an even surface.
I scraped off the excess varnish on the boom gallows and wet sanded in the by now usual fashion, from P400 through to P2500.
I followed that with polishing compound from P5000 to P11000, as in this pic.
I had already started to varnish the mast with a roller, tipping out with a foam brush, and had had great success.
So I decided to do the same with the rest of the spars. They were wet sanded with a P240 grit to tidy them up and returned to the house to await re-varnishing.
We live and learn ...