Clapper loader
From Tardis Wiki, the free Doctor Who reference
Clapper loader, or occasionally camera loader, known as the 2nd assistant camera on the Doctor Who TV movie, is a credit approximately equivalent to camera assistant in most BBC Wales productions. Their main responsibilities are operating the clapperboard at the beginning of each take, marking the actors as necessary, and maintaining all records and paperwork for the camera department. On film shoots, they would also be responsible for loading film stock.
To date[update], this credit has only been used in Class and in An Adventure in Space and Time.
Nick Watson was the 2nd assistant camera for the Doctor Who TV movie.
