The gallery wants to boost the number of people who purchase its £45 annual membership cards as Christmas gifts.
The account will be headed up by associate director Fiona O’Rorke, who will report directly to Stacey Ogg, individual giving manager, and the gallery’s press office, and will target national, regional and consumer lifestyle media.
The cards allow free entry to exhibitions at the National Portrait Gallery - which holds the most extensive collection of portraits in the world – as well as its collections at satellite venues in Yorkshire, Somerset and Wales.
Other benefits include the chance to attend members' events and discounts in the cafe and shop.
Delia Hyde, MD of Rain, said: ‘The National Portrait Gallery’s membership campaign is a wonderful addition and one which we are honoured to help promote.’