It was Labour's policy, granted, though they were following the advice at the time that diesel produced less CO2. Not sure it was Labour who then started falsifying data and misleading the public with defeat devices and cheat software. That was the profit driven, capitalist private companies.
dont think its fair to put the blame Labour. given other debates raging, its topical to higlight the source of the problem here is the EU, which set a bureacratic but technically weak emissions standard and have over seen decades of policy favouring CO2 reduction with little concern for other emissions. it was the 70's or 80's that they decided, to protect the French automanufacturers who'd heavily invested in diesel, to promote that fuel over other means improving fuel/engine efficiency (like variable valve timing the Japanese led with). when the global warming, CO2 reduction bandwagon rolled up it seemed like the right idea so they doubled up, because diesel has better energy density so better MPG and lower CO2. trouble is the other emissions are far worse than petrol, and now everyones realising they buggered up. now if we were out of the EU we could follow the scientist and engineers who knew and told us this all along...