Thanks for all the replies and advice. I thought the legislation could not be retrospective, but DRP are trying to mislead or confuse by quoting it in the letter. Ignore it is!

Thanks for the replies. I was hoping for a unanimous "just ignore it". Can the Protection of Freedoms act 2012 apply retrospectively? It's very uncommon for this to be the case. I addition to my first post, I should have mentioned that my son no longer lives at this address so I could truthfully mark any future correspondence as "moved away". In addition he sold the car identified in the Parking Charge Notice a couple of years ago, so DRP would not be able to find his current address from the DVLA. Maybe this is the way to go?

My son has received a demand for payment of £100 from Debt Recovery Plus concerning a parking charge notice issued in 2010 by Excel Parking Services Ltd. Following CAG advice, he ignored the original invoices and letters as he was not the driver of the vehicle at the time of the alleged incident, and up to today he heard nothing more. The letter from DRP quotes the Protection of Freedoms act 2012. I have looked at what I think is the relevant act (legislation.gov.uk/ukpga/2012/9/schedule/4/enacted) but it is too complicated for me to gain an informed opinion as I lack legal skills. Any advice as regarding how to proceed (or not) with this issue would be welcome.