We present an analysis of approximately 13-yr of observations of the intermittent pulsar B1931 + 24 to further elucidate its behaviour . We find that while the source exhibits a wide range of nulling ( \sim 4 - 39 d ) and radio-emitting ( \sim 1 - 19 d ) timescales , it cycles between its different emission phases over an average timescale of approximately 38 d , which is remarkably stable over many years . On average , the neutron star is found to be radio-emitting for 26 \pm 6 \% of the time . No evidence is obtained to suggest that the pulsar undergoes any systematic , intrinsic variations in pulse intensity during the radio-emitting phases . In addition , we find no evidence for any correlation between the length of consecutive emission phases . An analysis of the rotational behaviour of the source shows that it consistently assumes the same spin-down rates , i.e . \dot { \nu } = -16 \pm 1 \times 10 ^ { -15 } s ^ { -2 } when emitting and \dot { \nu } = -10.8 \pm 0.4 \times 10 ^ { -15 } s ^ { -2 } when not emitting , over the entire observation span . Coupled with the stable switching timescale , this implies that the pulsar retains a high degree of magnetospheric memory , and stability , in spite of comparatively rapid ( \sim ms ) dynamical plasma timescales . While this provides further evidence to suggest that the behaviour of the neutron star is governed by magnetospheric-state switching , the underlying trigger mechanism remains illusive . This should be elucidated by future surveys with next generation telescopes such as LOFAR , MeerKAT and the SKA , which should detect similar sources and provide more clues to how their radio emission is regulated .