There's lots of legislation on this: some of it less than sensible. Now, whether or not the plod would ever enforce it is another matter but I suspect there might well be a crackdown post Brexit.
Here's the gist of it with my emphasis and comments.
If you are a resident in the UK (which for this purpose includes if you just moved there with the intent of working and living in the UK), you cannot drive a non-UK car in the UK. (Well, legally, maybe but clearly tens of thousands do just that with impunity.)
Since there are no residency cards in the UK, (will that be coming post-Brexit?) whenever you are stopped by a police officer and he thinks you are actually a resident (for example if you have a UK driving licence, or have UK debit cards in your wallet), then he might confiscate your car which might be destroyed, unless you can prove you are not a UK resident, or you are working in more than one EU country, and spend more than 6 months (185 days) per year outside of the UK. (Like that's ever going to happen.)
If you are not a resident, then you can drive the car for at most 6 months (per year), but your car does need to have valid MOT and Insurance from the originating country, which you have to prove to the officer in case it's needed. You also have to prove to him that you are not driving the car for more than 6 months (for example if you show him the ferry/tunnel ticket). Every day your car is in the country counts, so if you leave the country, but the car is still there, it's still counts towards the 6 months (as your ferry/tunnel ticket is still showing the date). Exiting and re-entering the country won't reset the 6 months (although you will have a fresher ferry/tunnel ticket, so it becomes easier to prove you just arrived to the country) (The six-month thing applies throughout the EU and I have heard anecdotal evidence that the Spanish plod in particular are beginning to crack down hard on ancient old wrecks with UK plates that clutter up the Costas all year round.)
There are only three possible options for a UK resident to drive a non-UK car completely legally:
If the car is not yours, the registered owner is not a UK resident, and he is sitting with you in the car (in this case he is considered to be the driver) If the car belongs to (or to be more precise is registered in the name of) an EU-based company, and you are working for that company. If the car is on a lease in an other country (for example it's a car hired from France)
The second point is regulated by common EU rules on using non-local, but EU-registered cars abroad. Note that these EU rules also allow students, who are enrolled in UK and are only studying in UK for a set period to use their non-UK car. This is because they can be considered as non-residents.
The above means, that if you are a UK resident, and want to import your non-UK car, you cannot drive it even to get its MOT and registration, you have to tow it around, or ask someone who can legally drive it (e.g. a non-UK resident). (Except my neighbour, a UK passport holder and returnee from Spain had a left-hand drive Spanish-registered Nissan he used over here for around two years before he bothered to get it re-registered - so that's not policed either! You also see many foreign-registered cars belonging to contracted players or managers in English football club car parks. Bob Peeters Porsche Panamera on Belgium plates would have been a fine example of this)
A cynic would tell you that the rhd cars you refer to have been stolen over here, containered to wherever, get registered locally and are then sold on the cheap to people coming to the UK to work.
Comments
Here's the gist of it with my emphasis and comments.
If you are a resident in the UK (which for this purpose includes if you just moved there with the intent of working and living in the UK), you cannot drive a non-UK car in the UK. (Well, legally, maybe but clearly tens of thousands do just that with impunity.)
Since there are no residency cards in the UK, (will that be coming post-Brexit?) whenever you are stopped by a police officer and he thinks you are actually a resident (for example if you have a UK driving licence, or have UK debit cards in your wallet), then he might confiscate your car which might be destroyed, unless you can prove you are not a UK resident, or you are working in more than one EU country, and spend more than 6 months (185 days) per year outside of the UK. (Like that's ever going to happen.)
If you are not a resident, then you can drive the car for at most 6 months (per year), but your car does need to have valid MOT and Insurance from the originating country, which you have to prove to the officer in case it's needed. You also have to prove to him that you are not driving the car for more than 6 months (for example if you show him the ferry/tunnel ticket). Every day your car is in the country counts, so if you leave the country, but the car is still there, it's still counts towards the 6 months (as your ferry/tunnel ticket is still showing the date). Exiting and re-entering the country won't reset the 6 months (although you will have a fresher ferry/tunnel ticket, so it becomes easier to prove you just arrived to the country) (The six-month thing applies throughout the EU and I have heard anecdotal evidence that the Spanish plod in particular are beginning to crack down hard on ancient old wrecks with UK plates that clutter up the Costas all year round.)
There are only three possible options for a UK resident to drive a non-UK car completely legally:
If the car is not yours, the registered owner is not a UK resident, and he is sitting with you in the car (in this case he is considered to be the driver)
If the car belongs to (or to be more precise is registered in the name of) an EU-based company, and you are working for that company.
If the car is on a lease in an other country (for example it's a car hired from France)
The second point is regulated by common EU rules on using non-local, but EU-registered cars abroad. Note that these EU rules also allow students, who are enrolled in UK and are only studying in UK for a set period to use their non-UK car. This is because they can be considered as non-residents.
The above means, that if you are a UK resident, and want to import your non-UK car, you cannot drive it even to get its MOT and registration, you have to tow it around, or ask someone who can legally drive it (e.g. a non-UK resident). (Except my neighbour, a UK passport holder and returnee from Spain had a left-hand drive Spanish-registered Nissan he used over here for around two years before he bothered to get it re-registered - so that's not policed either! You also see many foreign-registered cars belonging to contracted players or managers in English football club car parks. Bob Peeters Porsche Panamera on Belgium plates would have been a fine example of this)
A cynic would tell you that the rhd cars you refer to have been stolen over here, containered to wherever, get registered locally and are then sold on the cheap to people coming to the UK to work.