The Britain's Got Talent judge and the Benidorm star were viewing An Audience With Jimmy Savile, a play about the disgraced U.K. radio DJ, at London's Park Theatre when Pemberton collapsed.

Walliams took to to praise Britain's National Health Service (NHS) after the incident.

He writes, "I had to take a friend to Whittington Hospital A&E last night. Doctors & nurses were excellent. Our NHS is something to be very proud of."

An insider tells U.K. newspaper The Sun, "There was a bit of a kerfuffle as Steve collapsed five minute before the end of the play. David Walliams stepped in to help him and ended up going to the hospital with him."

Other stars attending Wednesday's show included actor Bill Nighy and London Mayor Boris Johnson.