  We present updates of our results for neutral $B$-meson mixing and leptonic
decay constants obtained in the quenched approximation from a
mean-field-improved Sheikholeslami-Wohlert action at two values of lattice
spacing. We consider quantities such as $B_{B_{d(s)}}$, $f_{D_{(s)}}$,
$f_{B_{(s)}}$ and the full $\Delta B=2$ matrix-elements, as well as the
corresponding SU(3)-breaking ratios.
