Banned from driving in prison!?

My local freesheet, the North Wales Pioneer, has rather an odd criminal justice story in this week's edition. I can't find a link to the story in the paper's online edition at the moment, but this is the gist of the story:

A young man had rather a lot to drink and then assaulted his girlfriend. The police intervened, so the man stole the girlfriend's car in an attempt to make a get-away. He was cornered by the police and then used the stolen car as a weapon, driving into police cars and two police officers, before being apprehended.

In court he was sentenced to three years imprisonment for the assault on his girlfriend and the police officers and for stealing the car. He was also given a three year driving ban for the drunk and dangerous driving.

This is what I found odd about the story. My understanding is that prisoners in custody have no opportunity to drive. So if this man serves his full sentence he will not have had a driving ban in any practical sense. He will be allowed to drive himself home from prison on the day of his release! If he is given parole or remission on his sentence the practical time that he is banned from driving will have been shortened by the time that he will have spent in custody.

I can't see any logic in such a sentencing policy. Surely if a person is given both custody and a driving ban for a serious driving offence then the ban should always be consecutive not concurrent. It should start on the day the offender is released from gaol, otherwise the banning part of the sentence is just a nonsense that serves no purpose other than to make the law look like an ass.