The old Decca's were extremely variable, each one needing to be loaded to match it's particular performance. The current London's are much more consistent, and can be loaded according to builder John Wright's recommendations.
Noromance, the Decapod (why it is spelled with only one c I don't know) offers a couple of improvements. The "Pod" makes the cartridge less microphonic, being a thick slab of aluminum that replaces the much less non-resonant thin piece of tin that is the stock top plate of the cartridge. The Pod makes unnecessary the stock cheesy red plastic mounting bracket, a major source of weakness in the mating of arm and cartridge. The Pod is threaded, allowing for a tight direct fitting to the arm's headshell. The discarded plastic mount also contains the cartridge's output pins, which connect to thin strips of brass or copper (like the blades on the battery connections inside a flashlight) on the back of the cartridge body, necessitating an extra break and connection in the signal path. With the substitution of the Decapod for the stock mount, the output pins are on the cartridge itself, a huge improvement with a signal as low in voltage as that of a cartridge's, even the Decca's 5mV!
I believe the Decapod is available as a DIY part, or you may return the cartridge to have it installed by John. He will at the same time adjust and test the cartridge, returning it with a performance test report if I'm not mistaken. I wouldn't have a Decca without the Decapod!