One kind of gets used to progress marching along in a fairly linear direction. At times it jogs along rather too slowly. At others, it bolts alarmingly fast.

But progress is progress, and you know where you’re going with it: forwards. Which is why, when a reversal of progress is proposed, it feels so wrong.

I am referring to the suggestion last week that buses should be allowed to trundle along Cornmarket Street as they did 10 years ago.

Cornmarket is Oxford’s busiest street by far, where even walking is a challenge on busy Saturdays in summer and poor cyclists, wish as they might to weave through the throngs, are banned between 10am and 6pm. The idea that buses be readmitted to this hectic space is pure madness.

And it isn’t just a question of congestion. Bus engines may be cleaner than ever but the fact is diesel emissions are responsible for Oxford’s illegally high levels of noxious fumes. Levels of nitrogen dioxide have failed since 2005 to fall below the target of 40ug/mg (micrograms per cubic metre of air). In fact, this invisible killer is on the rise. By 2011 (the most recent available figures) the level was a shocking 61ug/mg – 50% higher than in 2005.

On Radio 4 last week there was a fascinating edition of Costing the Earth about how modern diesel cars emit far higher levels of some pollutants than previously thought.

Is the same true for buses? Whatever the answer, it is clear diesels and pedestrians should not mix.

The Cornmarket suggestion comes from the county’s two main bus operators and though it may at first appear to be a self-serving whim, it is actually a reaction to what they see as insufficient bus provision around the new Westgate Centre.

Cyclox should try to grab the headlines with a crazy scheme of its own. After all, cycle provision to and through the new Westgate is also rubbish.

Phil Southall, of Oxford Bus Company, said “radical thinking” was needed to strike a balance between direct bus links and pedestrian areas. But the idea isn’t radical, it’s retrograde. Radical would be closing South Parks Road/Longwall Street to private cars and having it as a bus and cycle lane only. And maybe taxis if drivers can manage not to break the speed limit. Buses could drop off in St Giles and then head along a re-opened Keble Road, around Longwall St to access High St. This would add a few minutes to the journey but create a realistic north-south route.

The city centre streets should be the domain of walkers, cyclists and load-carrying bikes making deliveries.