One in four used vehicles has a hidden history, according to vehicle background-checking website My Car Check.

It means that 25 per cent of used cars advertised for sale have either been stolen, have outstanding finance unpaid or been written off in an accident.

A write-off doesn't necessarily mean a car can no longer be on the road - and buyers must now get their head round a change to written off vehicle categories that arrived yesterday.

That may be more pressing depending on where you live. There are some locations in the UK where there's a higher percentage of damaged cars than others - and we've identified the ten write-off hotspots.

Write-off rankings: My Car Check has listed the top 10 UK locations with the most written off cars on the road

Morden in South London has been pinpointed as the UK capital with the most written-off motors, based on registered vehicles in the first half of 2017.

More than a third of cars in the area have been written off by an insurer, My Car Check revealed.

And it wasn't the only location in the capital to make the top 10 hotspots.

One in four cars in Barking, East London, and Northolt, West London, have been taken off the road by an insurance company after a crash, while neighbouring Canvey Island in Essex has a similar write-off percentage rate.

Cleethorpes, in Linconshire, took second spot as in the write-off rankings with three in 10 cars having a crash-damaged history. Doncaster, in South Yorkshire, made up the top three.

Watch out Londoners: As the infographic shows, London ranks highly for a high percentage of written-off motors

UK write-off hotspots rankings 1. Morden, South London - 35.4% 2. Cleethorpes, Lincolnshire - 31.4% 3. Doncaster, South Yorkshire - 27.1% 4. Barking, East London - 25.0% 5. Northolt, West London - 24.2% 6. Canvey Island, Essex - 23.5% 7. Gravesend, Kent - 22.8% 8. Corby, Northamptonshire - 22.2% 9. Rochdale, Grtr Manchester - 21.7% 10. Ramsgate, Kent - 21.3% Source: My Car Check

The top 10 hotspots were released as new insurance write-off categories came into effect on Sunday, 1 October 2017.

Following a consultation involving insurers, car manufacturers, the police and the salvage industry, the long-standing A, B, C and D write-off categories have been replaced with new codes.

In their place are:

Category A , or 'Scrap' cars, remain the most badly damaged vehicles. They can’t be repaired or even broken for spares.

, or 'Scrap' cars, remain the most badly damaged vehicles. They can’t be repaired or even broken for spares. Category B , or 'Break' cars, are again very badly damaged and beyond repair, but they can be ‘broken’ into parts for salvage and recycling.

, or 'Break' cars, are again very badly damaged and beyond repair, but they can be ‘broken’ into parts for salvage and recycling. Category S (formerly cat C) , or 'Structural' cars have incurred damage to the basic structure that gives a car its strength. These ‘S’ cars can be fixed and re-sold, but you should ensure that the work has been checked by a qualified mechanic.

, or 'Structural' cars have incurred damage to the basic structure that gives a car its strength. These ‘S’ cars can be fixed and re-sold, but you should ensure that the work has been checked by a qualified mechanic. Category N (formely cat D) , or 'Non-structural' cars, are equivalent to current Cat D cars. Their damage isn’t to the core structure, but there might still be some safety-related parts in areas like suspension or steering that will need to be replaced.

For a full breakdown of how the new write-off categories work and a guide to safely buying a category D - now category N - car, read our guide.

Mark Bailey, Head of CDL Vehicle Information Systems, which owns My Car Check, said London has been 'renowned' for having a high percentage of written-off vehicles and warned used-car buyers that almost one in four advertised models would at some point have been deemed too mangled to use on the road following a collision or vandalism.

'On average, over 18 per cent of vehicles we check are listed as having been involved in a crash, around one in every five,' he said.

'Leaving the safety aspect aside, there’s the impact on desirability and value. A category N write-off which has had cosmetic damage repaired should still cost substantially less than a similar vehicle with clear history.

'In a survey a couple of years ago, 79 per cent of My Car Check customers said they wouldn’t buy a write-off. That’s why it’s so important to check before you buy.'

Men more likely to write-off a car... and lie about how it happened According to Churchill Insurance, almost a quarter (24 per cent) of British drivers have written off a car during their time as a qualified motorist - that works out at around 10.9 million licence holders. After reviewing claims data, it said that men are twice as likely to be at fault for a collision with another car than women. As well as being more likely to have written off a vehicle, men are also more than twice as likely as women (48 per cent vs. 20 per cent) to lie about the details of the accident. Nearly one in five (19 per cent) have even gone as far as asking their children to lie to a partner about the circumstances of why the car has been deemed unfit to use anymore. The research found that the most common causes of car write-offs are accidents with another car (50 per cent), 'extreme' weather conditions (eight per cent) and a mechanical or technical fault (eight per cent). Of all write-offs, only a quarter (28 per cent) take place on main roads. Many (13 per cent) happen on country lanes, roundabouts (eight per cent) and car parks (five per cent). Blue car drivers should take heed as this is the colour of car most likely to be written off (18 per cent), closely followed by silver (15 per cent) and white and red (both 12 per cent), the insurer said. The younger generations are most prone to write-offs, with 18-34 year olds twice as likely to have their car written off than drivers aged 55 and over, even on familiar roads. Incredibly, 44 per cent of the younger age group have written their car off on the street they live on.

My Car Check said 18% of cars have been written off, but you might not be able to tell which cars have been salvaged while scanning the classified adverts

Category N cars will be easier to spot (if you check the paperwork)

One of the biggest issues with salvaged cars that had once been written off is that it is difficult to identify them from other, non-crashed, models without a thorough check. But this has has changed under the new rules.

The Association of British Insurers confirmed that any car that has been judged as a category N - meaning it is repairable and can be returned to the road - will have a black mark on its registration document to signify that it is a salvaged vehicle.

Any category N model will now have an 'S' on the V5C certificate (the registration document) and the following line to say: 'This vehicle has been salvaged due to structural damage but following a technical evaluation declared suitable for repair.'

This will give a clear sign to consumers that they should check repairs have been done to an appropriate standard, by investing in a vehicle inspection or using a recognised car history checking service.