Stewart Simonson was pleaded guilty to using the badge illegally when he appeared at Enfield Magistrates Court, having been caught by traffic wardens six months after leaving Ms Mills' employ.
He claimed that she often forgot to carry her permit with her when he was driving her, so he made a copy of it with her approval.
Unfortunately for him, traffic wardens noticed that the picture on the reverse of the permit was of a woman they "recognised from the TV".
In a statement to the court, Simonson wrote: "I was employed as a chauffeur by a lady who was awarded a disabled badge. On occasion she would forget to bring the badge, therefore I made a copy.
"I suffer from arthritis which forced me to retire. Six weeks before this I had been discharged from hospital and am in constant pain and unable to walk any distance and applied for a badge myself."
Simonson was ordered to pay £660 in fines and costs.
There was no suggestion that Ms Mills knew Simonson was continuing to use the permit.