My parents (indian citizens) are traveling from Delhi to USA transiting through London. They will be at heathrow airport for a couple of hours and will not need to exit the airport.
They received an email from british airways stating they need to complete a declaration form to travel onward to USA departing from the UK and need to declare one of the valid reasons. Is that really true? Does someone have experience with this? I can't imagine why this would be applicable for transit passengers