UK Transit Visa - Indian Citizen - Is visa needed?

[prasadramki]

MY brother is traveling from Chennai to SFO via London. He is an Indian Citizen and has a valid 10 year multiple entry visa. He will be transiting via London for 2 hours. Does he need a UK Airside visa.

Is there anyone who has recently traveled from India to US through the UK on British Airways who can provide their experience.

Thanks
Prasad