The service has deteriorated over the last few years but its still better than many other airlines.

Here's a trip report...a 2012 one
http://www.airliners.net/aviation-fo...d.main/217246/ Ignore the terminal at BOM. It's the old terminal. You will be using the new one.

LHR BOM and DEL LHR are operated by 777s. BOM BKK and BKK DEL are 737s.

Please do not expect the same standards as Thai.

1 hour between landing and take-off is a touch and go situation. It is definitely doable but if the incoming flight is delayed by a few minutes, you could end up missing your connecting flight. I don't know about DEL but LHR BOM is double daily and BOM BKK is also double daily. I think BKK DEL is also double daily but DEL LHR is a single daily flight.

If I were you, I would choose the other available options on LHR BKK. There are plenty of options and unless 9W is offering a very good fare, I wouldn't take travel on 9W on this route.