The counterpart was originally introduced to display driving licence details that could not be included on the photocard, including any endorsement/penalty points.
From today, penalty points will be recorded electronically and will not be printed on driving licences. Anyone who commits an offence will still have to pay a fine and submit their licence to court.
But I heard on Radi0 4's Today programme this morning that if you're going on holiday and planning to hire a car, you will need to obtain a special code, valid for 72 hours, which you will pass on to the car hire company before the hire car will be released. To get this code, you need your NI no. as well as your licence details. I expect this will catch out quite a few holiday makers this year and until this becomes more widely known.
For more info visit: https://www.gov.uk/government/news/driving-licence-changes