I am Indian national, residing in Qatar.
I am traveling to the US through London Heathrow (UK). My stopover at Heathrow is approx. 4 hours, before proceeding to US on same day of my arrival.
I will be changing terminals at LHR. I have no idea about the UK Immigration controls & baggage section also. I already booked/reserved my ticket with flight operated by American airlines/American airlines operated by Qatar airways.
Please let me know the whether TRANSIT Visa required for 4 hrs. stay at LHR before moving for onward journey to US.