On Saturday I had a go at one of the alternative challenges which is apparently not very popular, as there are only three times listed at http://www.explorerticket.co.uk/tubechallenge/southtop.htm. I figured that even if I was really slow, I'd still be in fourth place. Which is exactly what happened.
The challenge is visiting the 29 of the 270 tube stations which are south of the river Thames. Yes, there are only 29.
Start at Kew Gardens
District to Richmond, dep. 10:18:24, arr. 10:21:50
South West Trains to Putney, dep. 10:32:43, arr. 10:38:13
Walk to East Putney
District to Wimbledon, dep. 10:45:30, arr. 10:53:09
Bus 219 to South Wimbledon
Northern to Morden, dep. 11:07:17, arr. 11:09:40
Northern to Stockwell, dep. 11:10:31, arr. 11:27:03
Victoria to Vauxhall, dep. 11:28:56, arr. 11:30:46
Victoria to Brixton, dep. 11:32:51, arr. 11:37:28
Victoria to Stockwell, dep. 11:39:43, arr. 11:41:29
Northern to Borough, dep. 11:43:24, arr. 11:51:14
Northern to Elephant & Castle, dep. 11:55:38, arr. 11:57:23
Bakerloo to Waterloo, dep. 12:01:25, arr. 12:05:09
Jubilee to North Greenwich, dep. 12:09:58, arr. 12:21:14
Elapsed time = 2:02:50