24th October 2023:

I have discovered that a lot of the photo links have stopped working and have started fixing them -- so far I've checked and if needed fixed stations from A to P and will fix the rest over the next few days. [Update 25/10/2023: Have now checked and fixed up to T (inclusive), and also discovered that I forgot to acknowledge anywhere that I'd added photos of Royal Albert, so that's been fixed too.] [Update 26/10/2023: Have now finished checking and fixing the photo links.]

15th December 2015:

I am removing Street View as the embeds are proving unreliable -- I had started fixing ones that were showing an error page but some of the new embeds already don't work. The removal will happen over time in alphabetical order so expect stations in the lower reaches of the alphabet to still have (probably not working) Street View for some time. The maps will remain and those that are My Maps will be replaced with regular maps to allow access to Street View.

11th July 2015:

First Street View has been added to Emirates Greenwich Peninsula and Emirates Royal Docks, and there's new imagery of Embankment, Pudding Mill Lane and Southwark.

I am aware that an error page is appearing for some imagery, seemingly due to older embed code no longer working. If it becomes clear Google will not fix it so the older code works again, I will go through fixing them -- in the mean time, clicking the "View Larger Map" link will allow you to view any affected images.

25th September 2014:

New Street View has been added to South Kenton, Warwick Avenue, Waterloo, Theydon Bois, Stratford, Holborn, Marble Arch, North Acton, Victoria, Farringdon, Hammersmith (Hammersmith & City and Circle lines), Aldgate East, Kensington (Olympia), Prince Regent, Royal Albert, King George V, London City Airport, North Greenwich, Ruislip Manor, Hyde Park Corner, Hatton Cross and Tottenham Hale, plus first imagery of West India Quay, Mudchute and Pinner.

7th March 2013:

Google has refreshed its imagery again, resulting in first views of High Barnet, White City and Wood Lane, and additional views of Star Lane.

9th August 2012:

Google has added imagery taken inside most of the main railway terminals, resulting in new views of King's Cross St. Pancras, Paddington, Victoria, Charing Cross, London Bridge and Liverpool Street. They've also started updating existing imagery, resulting in first views of Stratford International, Stratford High Street, Abbey Road, South Quay and Shepherd's Bush, and additional views of Cannon Street, St. Paul's, Woolwich Arsenal, Stratford, Poplar, Westferry, Tower Gateway and Green Park. There's also first imagery of Stonebridge Park. Additionally a lot of existing views across the site will have updated.

Any Underground stations that have changed recently have now had their DirectEnquiries routes and associated photos updated, so stations such as Stratford, Green Park and Blackfriars are worth another look.

27th June 2012:

DirectEnquiries has now added National Rail Enquiries-style maps for most DLR stations, and I've therefore added links to them to the applicable station pages here. Incidentally, links to DirectEnquiries for route descriptions don't work at the time of writing as they are updating their London Underground information -- hopefully the links will start working again once they've finished.

21st May 2012:

It took a while, but I've now finished going through all the stations again. This time, Star Lane has it's first imagery, while Edgware Road, Dagenham Heathway, Wimbledon, Limehouse, East India, Royal Victoria, Custom House, Royal Albert, Finchley Road, Green Park, Bermondsey, Harrow-on-the-Hill, Woodside Park, Finchley Central, Highgate, Camden Town, Leicester Square and Oakwood have additional imagery.

I've also added links to Wikimedia Commons to all station pages for more photos, and links to National Rail Enquiries' station maps (which feature photos) to the pages of the stations that share at least a fair amount of the Underground/DLR station with National Rail (Amersham, Barking, Blackhorse Road, Chalfont & Latimer, Chorleywood, Ealing Broadway, Greenford, Gunnersbury, Harlesden, Harrow & Wealdstone, Harrow-on-the-Hill, Kensal Green, Kensington (Olympia), Kentish Town, Kenton, Kew Gardens, Moorgate, North Wembley, Old Street, Paddington (Circle and Hammersmith & City lines), Richmond, Rickmansworth, South Ruislip, Stonebridge Park, Stratford, Wembley Central, West Brompton, West Ham, Whitechapel, Willesden Junction and Wimbledon).

If you've tried to look at photos of Canary Wharf, Tower Hill or Westminster in the past and the links didn't work, but you didn't bother to tell me, I finally noticed this and fixed it recently.

Finally, I've found that DirectEnquiries has some great photos of Underground stations if you know how to get to them. I plan to add links to the station pages pointing to the appropriate pages on that website, but I'll do this over time, so for now you can access them by going here, selecting a station, then switching to the Access Information tab at the top -- you can then select a route with a lot of the steps in each route being accompanied by a link to a picture.
Update: DirectEnquiries links have now been added to all applicable stations.

February 2012:

Google has been adding new Street View over time where there previously was none, so I'm now going through all the stations again to look for good additional imagery. The things I do for you... Anyway, I'm starting with the Bakerloo and Central lines, and Debden has it's first imagery, while Buckhurst Hill, Woodford, Newbury Park, South Woodford, Snaresbrook, Leytonstone, Oxford Circus, Northolt and Harrow & Wealdstone have additional imagery