Thanks all! This gives me some good data points.
Any comments on the Virgin bar? Is that a big annoyance for people who want to sleep? Is it less of problem / less utilized on longer / overnight routes?
Treating London as the stopover and commencing the return journey in Paris (with < 24 hours in the UK on the way home) would very likely be less expensive because you wouldn't get stung for APD (UK departure tax).
Yup; that's what I found too when pricing these out.