We consider an inter-temporal policy game between changing governments that differ in their attitudes towards environmental pollution. When in power a government will choose policy instruments and set strictness of regulation with a view to influencing the policy of future, possibly different, governments. We demonstrate that a ‘grey’ government favours pollution permits over effluent taxes, as permits establish property rights that are costly to reverse. Conversely, a ‘green’ government prefers to regulate by taxes, in order to limit the incentives of future 'grey' governments to ease regulations. Strategic behaviour tends to exaggerate policy differences, making ‘green’ governments ‘greener’, and ‘grey’ governments ‘greyer’, than if such strategic considerations were not an issue.