Okay so there's an awful lot going on here - and as I'm sure you can appreciate quite a few chances where things could've been sorted. As it stands, while an MoT is valid for 12 months, it doesn't mean the vehicle will remain roadworthy for 12 months - just that the vehicle met the standard on the day of the test. There's also a rule of thumb that testers can only inspect what the can see. If you have concerns about the standard of the test carried out, then you can contact the DVSA and report the garage - that should be the first thing on your list. As for what happens next, it will depend on how much time and effort you want to expand on the situation.

The best thing to do here is to try and agree on something between you and the car's new owner. This could start with a third 'impartial' inspection if you have any concerns, you can then hopefully reach an arrangement. Buying a car privately doesn't give you the same protection of consumer rights you get buying from a dealer. If you buy privately, the car must match the seller’s description, be roadworthy and the seller must have the legal right to sell it to you. In this case, it didn't. However, the buyer is also responsible for ensuring the car is “of satisfactory quality’’ and “fit for purpose” before they buy it. Which in this case they didn't'. If you feel like you can't settle it between you, then you'll need to take legal advice and see whether or not the garage or the previous seller are liable.