Catalysed soot filter

A catalysed soot filter for a diesel engine, which filter comprising a wall flow substrate comprising an inlet end, an outlet end, a substrate axial length extending between the inlet end and the outlet end, and a plurality of channels defined by internal walls of the wall flow substrate, wherein the plurality of channels comprise a plurality of inlet channels having an open inlet end and a closed outlet end and a plurality of outlet channels having a closed inlet end and an open outlet end, wherein external surfaces of the internal walls of the plurality of inlet channels comprise a washcoat of at least one on-wall inlet coating composition that extends for an axial inlet coating length from the open inlet end to a downstream inlet coating end, wherein the axial inlet coating length is less than the substrate axial length, wherein external surfaces of the internal walls of the plurality of outlet channels comprise a washcoat of at least one on-wall outlet coating composition that extends for an axial outlet coating length from an upstream outlet end to the open outlet end, wherein the axial outlet coating length is less than the substrate axial length, wherein the outlet coating length is greater than the inlet coating length and wherein both the inlet and outlet coating compositions comprise at least one catalytically active metal as catalyst for increasing the percentage of NO2 of total NOx in exhaust gas exiting the catalysed soot filter as compared to NOx gases entering the catalysed soot filter.