That is the explanation that Wendy Neville, a spokeswoman for the London Transport Museum, gave the British Journal of Photography when they asked about a sign posted outside of the Aldwych Underground Station.
Which is … odd … when you consider that the sign prompting the phone call reads:
Due to their combination of high-quality sensor and high resolution, digital SLR cameras are unfortunately not permitted inside the station.
Which is also … odd.
The BPJ has filed a Freedom of Information request looking for more info.