Do we need a visa to come through London?

[sjsri]

Hi,
My MIL is coming to USA with visitor visa.
She is coming from chennai to philadelphia through london.
She is coming by british airways.
Does she need a transit visa?
Did any body came like this?
Can you please post your experience.
Thanks

[SidChan]

If your mom holds a valid us visa and return ticket, she does not need a transit visa....

for more info you can go to the UK consulate website where they've given all the details.

https://www.ukvisas.gov.uk

Hope it helps!