I'm ashamed to say, that continued searching has found that I had
already been given the answer to this earlier this year. But in a
different context and my initial searches didn't find it.
The answer is to put the Sweave code into an ERT box and start it with:
/SweaveOpts{keep.source=TRUE}
T
I have an Sweave/lyx document with a long line of code .
As an article (noweb), ctrl+return allows me to break up the code and
allow it to fit the page and still work as code.
I have pasted the text from the article class file into a new file that
uses the book class (noweb). But now the line