the UK doesn’t get to call a US citizen into parliment, we fought a war about that one.
I know American history classes suck, but I didn’t realize they sucked this badly.
Parliament can call summon anyone they like anywhere in the world. Whether or not the person they summon is required to go depends on local laws.
Believe it or not, even if the U.S. had a “you can’t summon us to parliament, so there” clause in the Constitution, the British could say “fuck your constitution” and do the summoning anyway.