The design of the Decca pickup creates an inherent electronic resonance. In the mid-1980’s I had a long conversation with the greatly-missed Harvey Rosenberg---a Decca fanatic and expert, during which he explained to me how an electronic damping circuit, created via resistive and capacitive loading of the pickup, was necessary to address and remedy the Decca’s electronic resonance.
Though the construction and build quality of the current London’s is a significant improvement on that of the old Decca’s, the pickup design’s inherent electronic resonance remains intact, still requiring an electronic damping circuit (resistance and capacitance) to provide anywhere near flat frequency response and non-ringing time-domain performance. The London Reference owners manual specifies 15kohms/220uF resistance/capacitance loading, the Super Gold 22k/220uF. Harvey used a lot more capacitance with his old Deccas. A LOT more.
The pickup’s mechanical requirements (arm tube and bearings, mechanical damping) are a whole ’nother matter!