Dr Peter Davies, a consultant physician specialising in respiratory diseases, drives a three-year-old Rover 200 owned by the hospital. His wife Eleanor drives a Toyota Previa and their 17-year-old son Richard an Austin Metro. Between them they drive the rest of the family - three more children and Dr Davies's father - 120 miles a day.
Every third weekend they have to drive 400 miles in the Previa to visit Mrs Davies's father. The rest of the time she uses it to drop off the two youngest children at school, do the shopping, drive her badly-sighted father-in-law to hospital, and travel to a north Wales college where she is taking a degree course in English.
Working at two Liverpool NHS trusts, Dr Davies says he needs reliable transport to get to his patients: 'It's a question of time. I have a highly pressurised job. If I'm going to see patients, I couldn't rely on buses or go by bike. I suppose I could use taxis but I don't think the hospitals would allow it as it's more expensive for them.'
Both parents say they are concerned about the environment and use unleaded petrol. But Dr Davies would not change his lifestyle because of threats of pollution: 'As a respiratory physician, if I was convinced there was a link between respiratory illness and me driving my car I wouldn't drive.
'But the relationship between asthma and car emissions globally is not very strong. The only logical compulsion which would make us think again would be to raise the price of petrol. If the price rise was absolutely crippling - say 20 or 30 per cent - I suppose we would consider getting rid of a car.'