Set the wayback machine to 1990s
"The mayor of London could follow the other cities like Paris etc and ban Diesel vehicles from central london"
Is there any analysis anywhere on the relative contributions from (diesel) cars, light vans, vehicles up to 7tonnes (sub-HGV), and HGV and above? Plus buses etc.
Instinctively based on what I see in Birmingham centre and suburbs, the contribution from diesel cars is relatively small (newer and better maintained vehicles, with DPF, etc), whereas the contribution from commercial vehicles, PSVs, etc, of varied ages and sizes (and qualities of maintenance) seems likely to be much higher.
In fact why not have another go at what Ken Livingstone's GLC quite understandably wanted a couple of decades (?) ago: ban all HGVs in the city and suburban areas unless specifically authorised (or, alternatively, zero tailpipe emissions, ho ho ho).