Below is the Cycle Hire docking station in Lower Marsh, near Waterloo.
So if you want to return your bike to Lower Marsh, you're forced to continue into Kennington Road and make a dicey right turn into Hercules Road. Forget about turning right into Centaur Street, that's a no-entry, so continue to Virgil Street. You might not fancy Virgil Street at night by the way, because it is effectively a narrow dark tunnel. If you don't get mugged then you'll turn right into Carlisle Street. This will take you back to Westminster Bridge Road, which you cannot cross to get back to Lower Marsh (unless you dismount). Realistically speaking, you will dismount and walk across the pelican crossing, however let's stick with the rules and say we have to cycle within the law rather than walk, which means you have to turn left into Westminster Bridge Road, go all the way round the York Road gyratory (a truly pant-wetting experience) and back up Westminster Bridge Road the way you came, and make a left into Lower Marsh. (Perhaps you could make a U-turn on Westminster Bridge Road, but that would be difficult and dangerous to accomplish).
So, in order to cycle legally, instead of cycling 100 metres west down Lower Marsh, you've had to take a detour of 1.5km. Is this a record? Remember, all these one-way restrictions are only there to stop motor vehicles getting in each others' way and keep the city from gridlock. There's no merit in applying them to cycles. Having introduced the Cycle Hire scheme, it really is time the Mayor faced up to the fact that London won't be a cycling city until the road system is designed as though cyclists exist.
UPDATE: I'd previously suggested there were no one-way signs on Lower Marsh - these seem to have been added since the Google Streetview pictures were taken. There's now a pair at the junction with Westminster Bridge Road.