Please are there any additional checks / screening for passangers who are transferring from an EU flight to an US-bound flight at LHR? Except the security screening as requested by the UK government.
The boarding pass will be issued before the first leg to LHR on the whole itinerary (all flights are under the same itinerary with one reservation number). The ESTA check should be done before the first leg at the first departure city (in EU).
Thank you.