Art Dudley talks about the Decca cartridge in the December Stereophile (I would provide a link, if only I knew how!). His review is of an older model, and the current London's are considerably improved, from the entry-level Super Gold to the Reference. They all put out 5mV, needing no more than 40dB or so of gain, and are best loaded with 15k to 22k Ohms resistance and 220pF capacitance (which electrically damps the design's high-frequency resonance). George Couness provides a 15k Ohm input on his Zesto phono amp specifically for the Decca/London!
As halcro, I too dislike unipivots, though they are recommended for the Londons by their maker. The cartridge has no suspension to speak of, so some form of damping is found beneficial by many users. Whether the chosen arm does or does not offer damping, it had better have a very stiff arm tube and chatter-free bearings, as the Londons put a LOT of mechanical energy into the arm. As Warren Gregoire told me, any arm that's good with a contemporary mc will be fine for the London.
I prefer the cartridge to all others by such a large degree (again, as halcro said, it is by far the most alive---I like the old Gordon Holt term "immediate"---sounding design I've heard), that I picked not just my arm to best suit it, by my turntable as well. The Townshend Rock could have been designed specifically for the cartridge, as it provides mechanical damping right at the source---the headshell. A side benefit is that the Rock's "outrigger" hardware adds 11 grams mass to the cartridge's 6 grams, aiding in balancing the arm and achieving a good resonant frequency, which is tricky---the cartridge's compliance in the lateral and vertical planes differ considerably.