Tom was right with his answer. Having recently set up a new mot station and completed the training, this issue was raised. Once a car has failed, you cannot drive other than to/from repairs etc. Many car sales outfits are now selling with whatever mot still exists. With the pre computer system, if it failed with 4 months remaining they could carry on using the old ticket. Nowadays, if it fails at that time, it is off the road.

HTH
Richard