her drivers license has old address
https://www.gov.uk/change-address-driving-licence
Possible £1000 fine if she is caught driving and it has the wrong address on it (depending on circumstances)
Depends on what the old address is, they just need one where you can be contacted. When I rented they advised that I kept my licence in my parents address to save having to update it as often.
@Ramsaye started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
https://www.gov.uk/change-address-driving-licence
Possible £1000 fine if she is caught driving and it has the wrong address on it (depending on circumstances)