Meet John Smith. John is a fairly average bloke. He’s 30 years old, married and has children under 16. John works as an accountant and is thinking about buying a new car.

Nothing flash, mind. He’s got his eye on a five-year-old Volkswagen Lupo, a manual, petrol-driven 1l model, worth a modest £1,000. And John is looking for insurance.

John is lucky enough to have a garage in which he plans to keep his new car at night. He wants it insured for social and commuting use. He’s held a licence since 1999, has no motoring convictions and has five years’ no claims bonus.

John, of course, is purely fictitious, and created by us in order to get a feel for the huge differentials in car insurance quotes depending on where you live.

According to a survey from one of the biggest insurance comparison websites, Confused.com, Bradford has seen average premiums rise by almost 50 per cent over the last 12 months.

And it all depends on which part of the district you live. We put the exact same details for our John Smith into Confused.com, but gave him different addresses. The difference was startling, with the cheapest insurance quote for John in one area more expensive than the top-end quote for a different address.

Perhaps unsurprisingly, John had the best chance of cheaper insurance when we gave him a BD23 postcode – Skipton. His cheapest quote for fully-comprehensive insurance was just £269.46, with the most expensive out of the 81 providers which Confused.com searched coming in at £656.25.

Witness the other end of the scale, where our Mr Smith lives in the BD3 area, around Barkerend. His best quote was £766.36 – more than a £100 more expensive than his worst Skipton quote. And the most expensive? An almost unbelievable £5,202.51.

We also got quotes for John for addresses in Bingley (BD16), Tong village (BD4) and Frizinghall (BD9). The differences in premium can be seen on our illustrative table above.

It would be bad enough, but some people from Bradford can’t even get insurance. Amir Ali, of Hendford Drive, is, unlike John Smith, very real. He has a BD3 postcode – Mr Smith’s least-competitive address.

Amir had been a customer with the major insurer esure through First Alternative, which provides insurance for higher-risk vehicles, for a year, paying more than £800 for his premium.

Shortly before he was due to renew his policy, he replaced his car and says he was told the vehicle could not be insured by the company.

Mr Ali, a father-of-four, blames the number of uninsured drivers in the area for the refusal.

He said: “I’m doing everything by the book, but people are driving without insurance and other people are having to pay for it. It’s not right.

“My premium keeps going up and up and up. Innocent people are having to pay for it. Nobody seems to be doing anything about it. More action needs to be taken.”

A spokesman for esure said the company was no longer seeking to insure higher-risk vehicles.

He said: “We have seen a mix in the cost of insurance premiums in the Bradford area with some rising, some staying the same and some going down. With 21,000 customers, we are still represented in Bradford.

“The problem is that the premiums cost the total of the claims paid out. Insurers have been paying out £1.20 in claims for every £1 they receive for some time, and claims are still rising faster than premiums. So in areas with a large amount of claims, the insurance premiums are going to be higher.”

Simon Lamble, product director at Confused.com, agrees: “The increasing cost of claims, which can be partly attributed to injury pay-outs for a new breed of litigation-savvy drivers, has seen most insurers struggle to remain profitable.

“The financial climate has also contributed to their problems, limiting insurers’ ability to make a healthy return on their investment of customer’s premiums. As a result, insurance providers are looking to drive up the cost to get themselves back into profit.

“The massive discrepancy between those worst and least-affected can be attributed to the frequency and cost of claims in each region. To put it simply, in areas where more is paid out, more has to be paid in.”

So as long as Bradford continues to have a negative image in terms of the quality of its motorists – in April, police announced they had seized more than 500 illegal vehicles from the streets of Bradford in a six-month crackdown on rogue drivers – we will all continue to pay the price.