previous work [@Paulsen_Wien] we have shown how the low-temperature quenched monopole populations of [Dy$_{2}$Ti$_{2}$O$_{7}$]{} obey the nonlinear and non-equlibrium response of monopole theory [@Kaiser2] that was developed assuming a single hop rate. In view of our findings, the theory should apply most accurately to the [Dy$_{2}$Ti$_{2}$O$_{7}$]{}  sample with no nuclear spins and least accurately to [Ho$_{2}$Ti$_{2}$O$_{7}$]{}  where the hyperfine splitting energies are of a similar order to the Coulomb energies. In other measurements, presented in Supplementary Figs. 7 and 8, we confirm that this is the case; hence a generalisation of the theory of Ref. to include the effect of nuclear spins seems an attainable goal. We also note that [Ho$_{2}$Ti$_{2}$O$_{7}$]{} offers the unusual situation that, at low temperatures ($<$ 0.35 K) and sufficient wait times, the nuclear spins are ice-rule ordering antiparallel to their electronic counterparts; hence spin ice offers a rare chance to investigate the effect of correlation on nuclear spin assisted quantum tunnelling in a controlled environment. Perhaps this will shed light on some of the unusual properties particular to [Ho$_{2}$Ti$_{2}$O$_{7}$]{}, as noted above.

Spin ice thus exemplifies a remarkable extension of the concept of nuclear spin assisted quantum tunnelling [@PS] to the motion of fractionalised topological 