LONDON.- The Alan Cristea Gallery, London presents an exhibition of rare Portrait Lithographs by Pablo Picasso, from 24 March until 21 April 2011. Lithography, a method for printing using a stone or metal plate, was a medium which fascinated Picasso; this exhibition charts the decade from 1945 which saw his most prolific period of activity in the medium through a tightly edited group of just 16 works representing some of the best and rarest examples on the market (prices range from £12,000-150,000). The majority of these works, many depicting his mistresses, were only produced as copies of successive stages of a stone or plate and as such never intended for public display and distribution; consequently these ‘artists’ proofs are highly sought after by collectors around the world. During the 20th century, a