2011-04-03 Sun - Cambridge ride. Fixed-wheel bicycle required

Tandems are fine on trains.
Kick up a stink and ask where is says you can't take one.
This has worked for me several times. Yes they block the doors, you just have to be considerate and move it as and when required.

If my tandem hasn't sold by then and I can find a stoker then I may well tandem it up as well.

Please also note the following aspects of our cycle carriage policy:

• We cannot carry tandem's, tricycles or bicycle trailers on any of our services. We simply don’t have room – sorry!
  
  

BUT

atob.org suggets tandems *are *permitted (and also for firstcapitalconnect (Kings X - Cambrige), which isn't contraindicated on fcc's website).