The Prime Minister's brother, Alexander Cameron QC, made an appearance in some of the first footage to be broadcast from the Court of Appeal since 1925.
More top news
London Paddington, which serves around 100,000 passengers each day, was almost deserted for much of Wednesday.
In the the op-ed, he warned governments in the Middle East “have been given free rein to continue silencing the media”.
The anonymous artist said the prank had worked “every time” in rehearsals.