  Earth's bow shock is known to produce non-thermal electrons which are
generally observed as a `spike' in their flux profile. Here, in this paper, we
present an analysis of electron and whistler wave properties for a
quasi-perpendicular shock crossing that is supercritical, but subcritical to
the so-called whistler critical Mach number, M$^w_{\rm crit}$, above which
whistler waves cannot propagate upstream. We have found that the amplitudes of
whistler waves increased exponentially as a function of time prior to the shock
encounter, while the suprathermal ($>$ 2 keV) electron flux similarly increased
with time, although with differing $e$-folding time scales. Comparison of the
electron energy spectrum measured within the ramp with predictions from
diffusive shock acceleration theory was poor, but the variation of pitch angle
distribution showed scattering of non-thermal electrons in the upstream region.
While not finding a specific mechanism to account for the electron diffusion,
we suggest that the whistlers seen probably account for the differences
observed between this `gradual' event and the `spike' events seen at shocks
with no upstream whistlers.
