New research by Irish company MotorCheck.ie suggests that tens of thousands of vehicles written off in the UK have been imported and registered in Ireland since 2014, some of them in dangerous and defective states.

The analysis, seen by Prime Time, was carried out by cross referencing the Vehicle Identification Numbers (VIN) of ex-UK cars registered here with the VINs in a database of written-off vehicles sold at UK salvage auctions.

MotorCheck's Shane Teskey told Prime Time: "We decided to take that database of three and a half million vehicles and cross reference every VIN number that's been imported into Ireland from the UK to see could any of those vehicles have made it across the water.

"We'll incorporate the history in the UK all the way along its ownership there and into Ireland. And that's why, when we ran that cross reference that those 36,000 cars emerged in a way that they haven't been seen before."

There is a wide spectrum of reasons for vehicles to be written off by insurance companies. Often, it's simply a case of the vehicle being beyond economic repair, meaning that the cost of fixing it would be greater than the vehicle's pre-crash value.

In Ireland, write-offs are divided into four main categories.

Category A is vehicles that should never again appear on the road, the frame and all parts must be destroyed.

Category B vehicles must also never be driven on the roads again, though some parts of the vehicle may be salvaged.

Category C are vehicles that have suffered structural damage, possibly to the chassis or crumple zone but can be returned to the road if repaired correctly.

Category D is similar, though these are vehicles that have suffered no structural damage but have sustained other damage that put them beyond economic repair.

The UK categorisation is similar to Ireland’s, though they have replaced Categories C and D with Categories S and N; S for "structural" and N for "non-structural".

The single largest cohort of write-off highlighted by MotorCheck as having been imported into Ireland is Category S.

Again, there's nothing wrong with cars of this category being repaired and returned to the road, provided those repairs are of a high standard and have returned the car to a roadworthy state.

For Shane Teskey, this is the crucial point. "We need to be safe and confident that the repairs have been carried out to a high standard. Secondly, if a car has a write-off flag against it, it's known to be worth at least 20% less than what an equivalent car that doesn't have a write-off flag would get."

The big question is whether the ex-UK write-offs being driven on Irish roads and for sale in Ireland have been repaired to that standard.

Using the data obtained by MotorCheck, Prime Time identified dozens of cars currently for sale here. Posing as buyers, we approached three dealers about buying the cars they'd advertised for sale. These were vehicles that had been involved in serious front-on crashes.

Prime Time also arranged for an independent assessor and engineer Liam Cotter to examine the cars away from the dealerships.

In all three cases, the engineer identified serious issues with the crash repairs and the current state of the vehicles. These ranged from a distorted track control arm that put the steering at imminent risk of failure to litanies of electronic faults, including in the airbag system.

One of the dealerships concerned told Prime Time that it believed it had bought the car in a roadworthy state and made the necessary repairs to the vehicle after being informed of the defects by Liam Cotter.

When we questioned the dealerships as prospective buyers, none of them informed us that the car had been written off, one didn't even mention that the car had been crashed.

The Competition and Consumer Protection Commission told Prime Time that: "It is a criminal offence for a trader to provide false or misleading information about crash history. It is also prohibited for a trader to omit or conceal material information from a consumer."

The CCPC does not comment on on-going investigations but Prime Time understands they are aware of the dealerships and cases featured in this report.

There are also written-off UK imports being sold by private sellers, a scenario in which consumers have very little protection.

A fact that motoring journalist Geraldine Herbert says people need to remember. "At least if you go to a dealer, the car has to be of marketable quality, it has to be as described. It has to be fit for purpose. And that's the key thing. It has to be roadworthy. So, you know, buying as a private buyer, you just have to be really careful."

With Brexit and other supply issues having pushed the cost of second-hand cars to unprecedented levels, due diligence is more important than ever. The three cars we inspected were flagged on both Motorcheck.ie and CarTell.ie as being written-off imports, but we also came across write-offs that some checking websites did not flag.

Some will give a green tick and say that a car hasn't been written off in Ireland, but it may also say that because the car is an import, it’s not possible to say it hasn't been written off elsewhere.

Some websites have access to information and databases that other websites simply don't have.

Geraldine Herbert stresses the importance of doing proper background checks before purchasing a car but believes that more needs to be done to protect all road users. "I think the issue of write-offs goes beyond consumer protection. You know, this is a safety issue. These are cars that we all share the road with. I think there should be something more, the State needs to step in here."

The UK is currently ahead of Ireland in that there is a shared insurance database, albeit a voluntary one of written off vehicles.

Ireland has no such equivalent.

It means that vehicles that have become more difficult to insure and put on the road over there can have an easier time making their way to Ireland, where there will be no official examination of their repairs or assessment of their roadworthiness before they're put on the road.

For Liam Cotter, it's unacceptable that vehicles can be brought in from another jurisdiction where they've been written off and put on the road or sold in Ireland without any official examination of the quality of repairs, particularly in scenarios where the dealer refuses to disclose the full history of the vehicle.

"We picked three cars for the purpose of this programme and all three, and in my opinion, they're not in good condition. As far as I'm concerned, they're not roadworthy. There's a lot of, of very serious defects in them. If that's a snapshot of the real situation, then this is quite serious, given the numbers you're talking about."