So what is the excuse of the current party in power ?
Same as usual, sadly, that Election Funds and Influence and Lobbying are all inter-related. But I, for one, would appreciate a bold politician, rather than a Spin and How-Do-I-Look artist.
The opposition party was duped
Certainly in part, but plenty of their own advisers were aware of NOX / particulate problems, but for whatever reason Government was "persuaded". Perhaps by German Auto that e.g. catalytic converters would solve the problem ... but in that case where's the Contract / comeback on those suppliers who failed, lied and cheated?
But on balance I think UK is doing OK on this front. Yes, definitely could do better, and whoever is on the other side in any political debate , e.g. Greens, will always complain "not enough", and I have plenty of "not enough" gripes, but short of a Bold Leader then medium-steps is the limit of my expectation and I am content with that whilst, personally, doing way more than the norm ... and, according to my wife, preventing us getting invited to dinner anywhere because I harang my hosts about using their Range Rovers for the school run
By by comparison I don't see USA being in a good place, failure to implement fuel prices as seen in the rest of the world means that energy use is profligate, and desire to e.g. insulate (or install PV / change to more frugal cars etc.), instead of just using more energy, is low compared to "over here". As I understand it Diesel was never a thing, for cars, in USA because refinery output was not readily available, so good thing for USA and, yes, our politicians got suckered by German Auto ... and have imposed NO Penalties over Dieselgate (another good job done by USA)
On Climate change my gripe with UK is that the requirements for Building regulations are woefully inadequate. We could make a huge dent on our oil imports by improving insulation of New Builds. Such standards are common on the continent (I don't know if enforced, or just "obvious"). Our house is Passive House standard, so needs virtually no heat in Winter (nor cooling in Summer, although [domestic] AirCon is not really a thing here); Why would we not build all houses that way? On average 7% additional capital cost, winter fuel reduced to close to nothing, and no boiler maintenance / renewal for the lifetime of the building ...
Retro-fit to Passive House standard is a nightmare, hence my gripe that New Builds are not required to be a much higher standard.