This has turned out to be a better tip than I thought. I’d forgotten there was an Inline mode, which is making a beautiful job of reversing my earlier c-u.
For those of you who don’t know the plugin - it’s free and available in 64- and 32-bit versions - there are three modes.
Encode: l/r → m/s
Decode: m/s → l/r
Inline: l/r → m/s → l/r *
- Essentially it allows you to rebalance the stereo width on the fly. Hello again, clarity!
Bit of an essential piece of equipment that I now understand the use of so much better than I did. Thanks, Woodcrest, you are the man!
Cheers,
A very 
C