The account was previously held by PPS but has changed hands following the move earlier this month of PPS director Richard Mollet to GPC.
PPS will continue to advise the car park operator on local government and planning matters.
Mollet, who is a senior policy adviser at GPC, reports to NCP marketing director James Holbrook on the account.
Mollet said the media relations work would concentrate on the local government and trade press. In terms of public affairs, the key government departments are the Office of the Deputy Prime Minister, which is currently reviewing planning legislation, the Department of Transport and the Home Office, which co-ordinates CCTV and vehicle crime reduction initiatives.
Stakeholder groups that are targeted as part of national PA work include the Society of Motor Manufacturers and Traders.
Assisting Mollet on the account is GPC consultant Stephen Day.
NCP, which runs more than 500 car parks nationwide and has a property portfolio worth £392m, is looking to increase its role in private-public partnerships.