As stiff an armtube as possible benefits ALL cartridges, but the Decca/Londons, having no rubber damping suspension (and no traditional cantilever; the stylus is attached to a V-shaped metal plate, which goes straight up into the cartridge) benefit most of all. The D/L’s transmit a LOT of mechanical energy into the arm, exacerbating any armtube flex and/or bearing "rattle" present in any given arm. The Zeta is known specifically for its’ strengths in those two criteria.
The front-end damping provided by the Townshend Rock is exactly what makes that table so appropriate for use with Decca/Londons. A damped arm has long been recommended for use with the cartridge, and I have had a few; the Decca International, the Mayware Formula 4, and a modified (with damped bearings) SME 3009 Improved. The Rock makes a damped arm unnecessary (and in fact the front-end damping afforded by that table is a better way to damp than applying it at the back end of the arm), allowing armtube stiffness and superior bearing design & build to be prioritized. The Rock comes with a metal arm mounting plate drilled for the Linn/Zeta arms, which share the same pivot-to-stylus distance. The plate even has the six holes required by the Zeta’s arm mounting collar---very handy. I added a layer of thick acrylic under the metal plate, as that plate is a little too ’lively" for my liking. Yes, I believe in damping resonances!