I thought it was only dangerous failures which prevent you from driving away from the test centre and that major failures just mean that you can't continue to drive it if the old mot is still valid.
I'm looking at joining the dark side and buying a BMW mini clubman to be able to tow them if necessary. I need to get a b+e licence first though!
I have a new F54 clubman for every day and you will not need a B+E to tow as the car trailer and a classic mini is under the MAM of 3500Kg
I have a licence to tow however I went on a weigh bridge and there is plenty of scope for more weight
Just be careful because I think that they take the plated weights of cars and trailers rather than the actual.
For example you could have a 1500kg car with a 400kg trailer with a 650kg mini which is much less than 3500kg and the trailer and load (mini) are less than the weight of the car (which I believe is also a requirement), however, if the trailer has a plate on it for 2100kg then they will say you are overweight.
I use a homemade trailer (built around 30 years back) which isn't plated so they can only assess it on its actual load.