score:3
You probably don’t need a visa to transit via LHR if travelling to/from the US with a valid visa. The UK government’s “check if you need a visa” tool states, even in the case where you need to go through passport control:
Transiting without a visa
You may be eligible to transit without a visa if:
- you arrive and depart by air
- have a confirmed onward flight that leaves on the day you arrive or before midnight on the day after you arrive
- have the right documents for your destination (eg a visa for that country)
One of the following must also apply:
- you’re travelling to (or on part of a reasonable journey to) Australia, Canada, New Zealand or the USA and have a valid visa for that country
- you’re travelling from (or on part of a reasonable journey from) Australia, Canada, New Zealand or the USA and have a valid visa for that country (…)