We often use our local bike shops for the odds and ends that we always find ourselves short of at those critical moments.
The closest to us and therefore, most frequented, is Crazy Horse Bike Workshop in Tooting who tweeted recently that they had completed the build of Steve's 61cm Handsling Bikes RR1.
Here it is in their well stocked shop on Balham High Road. It is finished with an 11-speed Ultegra groupset and 40mm deep Handsling Bikes carbon wheels
Follow them on Twitter at CrazyHorseBikes.