Dear Daniela, we hate dSLRs because they're professional. Love, TfL

Here it is, fresh from my inbox, the statement from Transport for London (TfL) clarifying just why dSLRs were banned from the tour of the disused Aldwych underground station over the weekend. Please make sure that you're sitting down and do try to refrain from punching in your screen.

Terms and conditions for the recent sale of tickets to visit Aldwych Underground station clearly stated that digital SLR cameras were not permitted, as these are classed as professional equipment.

There was not a ban on taking photos during tours. However, there were restrictions on professional cameras and tripods because we were concerned that people using them could delay the tours for others, as it was a very tight schedule with more than 2,500 visitors going up and down a spiral staircase of about 160 steps to get to and from the platforms.

We wanted to make the tours as enjoyable and safe as we could for everyone. With the huge public interest in seeing the disused Tube station it was better to have the event with this restriction rather than no visit at all.

We apologise to visitors who wanted to use this kind of camera during tours to the stations.

TfL has, in its infinite wisdom - for the wisdom of a transportation authority must be infinite - classified a dSLR as professional equipment and in doing so, redefined the professional standing of millions of photographers across the globe. What an astonishing turn of events! I'm sure that all the dSLR-owners amongst us must be delighted to know that whatever your previous experience or qualifications you are now, according to TfL, professional photographers. Congratulations!

I find it even more astonishing that this through-the-lens, at-the-speed-of-light optical device also makes us slower to move through an exhibit. This is especially strange, given that the last time I checked, I was generally faster using my dSLR than my compact. Something to do with not having an electronic viewfinder, a speedier autofocus, and a more powerful processor. Maybe I need to invest in a new, professional-grade timekeeping piece to check that? Maybe that would qualify me to work at the Olympics next year? I could time Usain Bolt!

I'm not sure which type of camera TfL was mistaking a dSLR for, but I'm pretty sure that the necessity to use a tripod went out with the wetplate camera. Maybe they have one lurking down there in Aldwych station still?

I'm almost, but not quite, speechless. The general degree of ignorance and naivety on the part of people making these decisions is marvellous. A small dose of logic and some reasoned thinking, perhaps alongside a phonecall or email to some people who actually know, would have saved them from a great deal of embarrassment and the entire photographic community pointing at them and laughing.

Yes, that's right, TfL, we're all having a very sound belly laugh at your expense.

All photos courtesy of Tim Allen, and taken with his LX3.