Pablo Picasso (1881-1973) was probably the single most influential and important artist of the C20; any significant exhibition of his work is therefore an important occasion and worth careful study. Given that the human figure is such a dominant subject in Picasso’s work, you could argue that practically any exhibition of his work must be in part an exhibition of portraits. Indeed, the last exhibition of portraits in New York some years ago apparently got lost simply by bringing too much work into scope. This current exhibition at the National Portrait Gallery avoids this by focusing on portraits of known subjects, primarily his friends, family and lovers. The result is a tight, manageable exhibition which reveals yet again Picasso’s greatness. You leave the exhibition stunned by his ability to move between styles, to use those differing styles to reveal so much about the subject and his relationship to them, and by his relentless competitive drive to show himself the equal of any past or contemporary artist, by taking on and equalling anything they can do.

The exhibition also reveals a side of Picasso perhaps not so well known with the brilliant caricatures through which he represented so many of his artistic contemporaries, particularly when he first settled in Paris. These caricatures, one cannot help but think, served two purposes. Firstly, they quickly demonstrated his talents and capabilities and established himself as a force to be reckoned with. Secondly, they served to establish him as a dominant and controlling figure, able to shape how others were seen. It is hard to avoid the sense that caricature was a key part of establishing Picasso as the alpha male in his circle.

By 1909, Picasso was immersed in Cubism and beginning to examine how Cubism could be used to reshape the traditional portrait. The resulting pictures are perhaps the most important and influential in the exhibition, most notably the portrait Daniel-Henry Kahnweiler painted in 1910 and representing one of the most radical departures in portrait painting. But what is almost more extraordinary than the painting itself is where Picasso went next.

In 1917, Picasso met Olga Khokhlova, a Ukrainian ballerina with the Ballets Russes in Paris.  They were married in 1918. That same year he produced Portrait of Olga in an Armchair, a tender neo-classical portrait that seems to have been heavily influenced by the work of Ingres some hundred years earlier. This is a portrait which tells of love and intimacy.

Five years later, there is a second major portrait, also developed entirely in the classical tradition. Olga sits on a chair in a sober, brown suit looking pensively into the middle distance. It is a portrait which creates a sense of Olga as elegant and refined, but also as closed, and somewhat remote. It is no surprise therefore to learn that the marriage is already in trouble and the couple increasingly estranged.

The final portrait of Olga in the exhibition was painted in 1935, the year they were divorced, and a portrait we can safely assume was not painted from life. This is a distorted, almost tortured image of Olga, still recognisably her with the small mouth and pensive eyes but reduced to a modernist caricature with a pencil neck and a stylish hat which seems misplaced and inappropriate.

Three portraits, three styles, each selected to tell us about how Picasso saw the subject at the time the picture was painted, and in doing so revealing as much about Picasso’s state of mind as about the subject. Whether in pencil sketches or complex oils, the trajectory of his friendships, his loves and relationships are laid out as clear as day in picture after picture.

In addition though, a relentless competitiveness is repeatedly displayed, whether in paintings derived from Old Masters he admires or that wish to demonstrate that he can match any of his contemporaries at their own game. One such picture is Woman in a Yellow Armchair, a portrait of another muse, Marie-Therese Walter. This picture was exhibited exactly one year after Matisse had held a major exhibition in the same location and the picture is flagrantly Matisse in its flattened surfaces and bold, primary colours. I can do that as well as you, Picasso is declaring.

Overall, this is a beautiful exhibition, big enough to give a broad sense of Picasso’s range and depth, small enough to be readily absorbable. No doubt there are omissions, and some critics have complained that there is too much ‘classical’ portraiture and too little of his Cubist-influenced work. I am not in a position to comment ther than to say whether or not this is true, it remains a must-see exhibition.