Highlights from Photo London 2017 - virtual reality meets vintage treasure

At heart, Photo London is a selling fair for expensive photographic prints. You wander through the steamy labyrinth of Somerset House from gallery show to gallery show surrounded by black-clad snapperati, assaulted on all sides by images until lost in photography.

This year the show is said to be the subject of a "rigorous curatorial process" designed to show rare historical treasures, new work by established masters, and work by the brightest new stars. But surely I saw that print here last year? And didn’t I see that Karsh portrait of Winston Churchill on a five-pound note?

There are great photographs, not so great photographs and photographs which are not great at all in a seemingly endless series of rooms. After turning left, right and left again, and ending up in the same room three times running it was time to puzzle out the map and try the set pieces. Matt Collishaw’s Thresholds (pictured below) uses virtual reality to recreate Henry Fox Talbot’s landmark 1839 exhibition, when his photographic prints went on show for the first time.Kitted out in a mask, headphones and backpack you walk into a grey room which suddenly becomes a Victorian gallery three times as large with glass vitrines, a blazing fire and virtual mice running around. My fellow visitors appeared as shining pillars of light which put me in mind of the angels set over Eden, at least until I bump into one and it turns out to be my editor. It has to be said that I couldn't see the exhibits very clearly but this is how new things begin.

The public programme features work by Taryn Simon, William Klein and Isaac Julien, with Julien's landmark film Looking for Langston, 1989, now something of a classic, the focus of his exhibition. Taryn Simon is this year's Master of Photography, an accolade that honours the cutting edge nature of her work. Working with a programmer, Simon has produced Image Atlas, a project that explores cultural differences and similarities by indexing the top image results for search terms entered into local engines throughout the world.

Juergen Teller has an exhibition in the Great Arch Hall, his images hung, as usual, without frames in a seemingly random way. One picture of a ostrich caught my eye. The caption reads as follows: Safari Ostrich, At Moments I Felt like Being in a Strange Dream in a Medieval Forest with 2 Naked Canadian Girls Doing Hula Hoops, covered all over in Sweet Maple Syrup. Research has revealed that this had something to do with a shoot in a Canadian cannabis factory.

Finally I penetrate to the Embankment level and reach David Hurn's Swaps. This is a delight. A giant of documentary photography, Hurn is a veteran of Magnum Photos. When a new photographer joins the agency they receive a letter from Hurn, offering one of his prints in exchange for one of theirs. By this simple device he has, over six decades, built up a collection of photographs from some of the world's best photographers without paying the amazing prices he would have had to pay at Photo London. Co-curated by Martin Parr, each of Hurn's photographs is surrounded by the pictures he chose to swap them with (pictured above right: Christopher Anderson, Hillary Clinton at the Liberty Awards, 2013). They are by turns witty, charming, powerful and moving. Sometimes the swaps seem to be visually connected, sometimes they are a strong contrast, but in all cases they are images chosen by photographers for photographers, and it shows. And then something rather wonderful happens. As if by magic the great man himself appears at my side. It is David Hurn, in person. I tell him how much I like the show. He modestly demurs. I insist. He seems pleased. It is all very satisfactory.

• Photo London at Somerset House until 21 May
• Mat Colishaw: Thresholds at the River Rooms, Somerset House until 11 June 2017
• Read more visual arts reviews on theartsdesk

@williamjlknight