Self portraiture is a tricky business. It can be a practical choice: an artist’s face may simply be the only one in the studio at the time. It can be an act of egoism and control: defining for posterity how an artist wishes to be presented to the world. And often it’s a line of inquiry, investigating all the permutations of identity and self.

Xavier and Mark put together this romp through art history with slides, looking at ways masters from Velasquez to Hogarth to Courbet have controlled their own images. Arrogance, wit, self deprecation, honesty, bravado, vulnerability. The many faces of humanity come through in self portraiture as much as they do in any subject. The historical precedents are nice backdrops for a conversation that reflects on Mark’s own forays into self portraiture. The conversation goes in and out of focus for me as Mark occasionally halts the flow while he searches for the way he wants to answer the questions. Xavier knows – as anyone who knows Mark knows – that the answer will be worth waiting for. But I don’t think I’m the only person in the room who feels nervous for Mark – and for Xavier – when his pauses get a little too long. I’m slightly anxious that some internal chaos may prevent Mark from rescuing us all from this awkward silence.

Each time, though, Mark comes through, in quips, amusing personal anecdotes, references to English political history, Christian doctrine, and his own enthusiasms for horse racing and music. Xavier has placed Mark’s “I” sculpture next to Van Dyke’s painted self portrait, but there is no ego in sight. He’s clearly interested in the question of how he represents himself, but it’s always more of a performance or a proxy than a presentation. There he appears, for instance, in his video Angel, dressed as the character Blind Faith in nondescript black trousers, white shirt, black tie and sunglasses, reciting “in the Beginning was the Word,” in reverse on an escalator; and there he is again, in Sleeper, dressed as a bear, alone and seemingly trapped in the glass-fronted and empty Neue Nationalgalerie in Berlin, performing for the passersby. He has scrawled his signature hundreds of times in chalk on bricks throughout London, making his “MARK” across the city, and now, more recently, he has painted his dozens of “I”s – “self portraits” that aren’t even particular to him, but could apply to any one of us. Like the conversational pauses that signal an honest struggle for the authentic answer, most of these self-presentations are a proxy for the real person who remains at a distance, just out of reach. We sense the presence of Mark through his absence.

Wallinger purposefully chooses Times New Roman for the font of his self-scaled sculpture “I,” that stands in the galleries at Dulwich. The one-letter word we all share to describe ourselves looks so classic, legible, in a word – presentable – in this font. It’s a humane choice. If anything, these recent renderings of the letter “I” have a universality to them that may be more about “we” than him. It feels as though he were speaking for us all. And in this self-effacing way, Mark makes the act of self portraiture more like an act of altruism than egotism.