Lhr - Bom
Being a pilot & working in India, I use this route quite frequently, albeit usually from BLR.
I tend to use BA as often as possible, & generally travel in Club world. Frequency from BOM is good - 2 flights a day, however, usually running with high traffic loads.
Don't use VS because I don't like their service.
Jet Airways is worth a look - their new Premiere service is akin to VS layout in Upper Class, but with a much better service. If you can afford to push the boat out, their First class suites are wonderful.
Alternatively, if you don't mind a stopover, I've heard good things about Ethiad's new "Pearl" / Business class service. Maybe someone can clarify that.
Regards
HPC