There’s an occasional debate on whether photography is allowed on the Tube, generally sparked when a staff member harrasses someone for doing it.
The answer is crystal clear: photography is indeed permitted on the Tube without express permission, as long as you don’t do anything dangerous like using a flash, or sell the pictures you take.
TfL’s website confirms that photography on the Tube is allowed for personal use. This is supported by part 10 of rule Sa109 in staff’s Working Reference Manual (I don’t have a copy, but anyone hassling you should), which says:
10.1 Passengers can take photographs with small cameras for private purposes, provided
* flashlights and/or tripods are not used
* No obstruction or inconvenience is caused to staff and/or passengers.
10.2 Representatives of the media, press or photographic agencies and film companies, and other persons taking photographs for commercial purposes must first get permission from the Press Officer.
I think the only reason this is an issue is that the TfL page on commercial photography is easier to find than the one on general photography, and hence one gets mistaken for the other. Hopefully this post will help direct people to the right places…