An exhaust system for a lean-burn internal combustion engine, which system comprises: (i) a first catalysed substrate monolith comprising an oxidising catalyst on a flow-through substrate monolith for use in treating exhaust gas emitted from a lean-burn internal combustion engine, which flow-through substrate monolith having a first end and a second end and comprising a metal or ceramic honeycomb monolith having an array of elongate channels extending therethrough, which channels are open at both ends, which catalysed substrate monolith comprising a first washcoat coating having a length L extending for an entire length of channels in the substrate monolith and a second washcoat coating, wherein the second washcoat coating is disposed in a layer above and covering the first washcoat coating for some of length L and is arranged in a zone of substantially uniform length at the second end of the flow-through substrate monolith, which zone being defined at one end by the second end of the flow-through substrate monolith itself and at another end by a point less than the entire length of the first washcoat coating, wherein the first washcoat coating comprises a catalyst composition comprising platinum and at least one support material for the platinum, wherein the second washcoat coating comprises a catalyst composition comprising both platinum and palladium and at least one support material for the platinum and the palladium, wherein a weight ratio of platinum to palladium in the second washcoat coating is ≤2 and wherein a Pt:Pd weight ratio of both the first washcoat coating and the second washcoat coating combined in the catalysed substrate monolith is ≥1:1, wherein the first end of the flow-through substrate monolith is oriented to the upstream side; (ii) a second catalysed substrate monolith comprising a selective catalytic reduction catalyst, which second catalysed substrate monolith being disposed downstream from the first catalysed substrate monolith; and (iii) an injector for injecting a nitrogenous reductant into exhaust gas between the first catalysed substrate monolith and the second catalysed substrate monolith. (i) a first catalysed substrate monolith comprising an oxidising catalyst on a flow-through substrate monolith for use in treating exhaust gas emitted from a lean-burn internal combustion engine, which flow-through substrate monolith having a first end and a second end and comprising a metal or ceramic honeycomb monolith having an array of elongate channels extending therethrough, which channels are open at both ends, which catalysed substrate monolith comprising a first washcoat coating having a length L extending for an entire length of channels in the substrate monolith and a second washcoat coating, wherein the second washcoat coating is disposed in a layer above and covering the first washcoat coating for some of length L and is arranged in a zone of substantially uniform length at the second end of the flow-through substrate monolith, which zone being defined at one end by the second end of the flow-through substrate monolith itself and at another end by a point less than the entire length of the first washcoat coating, wherein the first washcoat coating comprises a catalyst composition comprising platinum and at least one support material for the platinum, wherein the second washcoat coating comprises a catalyst composition comprising both platinum and palladium and at least one support material for the platinum and the palladium, wherein a weight ratio of platinum to palladium in the second washcoat coating is ≤2 and wherein a Pt:Pd weight ratio of both the first washcoat coating and the second washcoat coating combined in the catalysed substrate monolith is ≥1:1, wherein the first end of the flow-through substrate monolith is oriented to the upstream side; (ii) a second catalysed substrate monolith comprising a selective catalytic reduction catalyst, which second catalysed substrate monolith being disposed downstream from the first catalysed substrate monolith; and (iii) an injector for injecting a nitrogenous reductant into exhaust gas between the first catalysed substrate monolith and the second catalysed substrate monolith.