evolution? Fresh era? Not long ago bus services in Oxford were mainly run by one company, so that ticketing problems were non-existent.

There was easy interchange between routes, in contrast to the lack of connectivity across the centre that nowadays often drives people into their cars.

Technical advances over the past few decades have produced cleaner, more efficient vehicles, and electronic systems that are partly replacing the cashier/drivers or bus conductors (remember them?). But the revolution of privatisation produced a number of losses.

Many routes see no competition.

Bus companies can choose when and where they run services, and there is little incentive to provide the connectivity for the seamless journey that most of us seek.

So what should be the next era?

In some cities the public transport network is determined by a passenger transport authority, which can design easy interchange between bus and rail travel and cycling, making it easier to use for residents and visitors alike.

Private companies then compete to provide the services on parts or the whole of this network.

It happens very successfully elsewhere, so, taking a hint from the geologists, maybe we should follow the pre-Thatcherian era and the current post-Thatcherian era by the Swiss, or Helvetian, era?

Dr Andrew M Pritchard, North Hinksey, Oxford