Just Stop Oil protesters also interrupted MPs on the home affairs committee.
"The right to protest peacefully in the UK no longer exists," Graham Smith said.
Scotland Yard said they arrested people on suspicion of "breaching the peace".
The anti-monarchy group Republic told HuffPost it plans to protest Charles and Camilla's upcoming appearance in York on April 6.
Why Both Sides Of The House Have Taken Staying In The Single Market Off The Table Is Beyond My Comprehension
I expected my amendment to lose, but I didn’t expect my own party frontbench to aid and abet them