Thomas Lawrence

One of the delights of this exhibition is the opportunities it provides to work out how some of the effects are achieved: the portrait of Elizabeth Farren for instance features a shimmering gown, courtesy of thickly applied brushstrokes of white paint. So simple, yet so effective. Not that the clothing dominates, impressive though it is. His drawings provide ample illustration of Lawrence's skills and the faces are what you most remember. Selina Meade and Rosamund Croker are impossibly beautiful, though not forbiddingly so, while the elderly Mary Digges shows how adept Lawrence was at portraying age. Likewise the oil sketch of Wilberforce is full of character, while the painting of Pius IV is a worthy descendant of Raphael's Julius II. Perhaps most charming of all are the portraits of children, whether on their own like the famous one of Charles William Lambton, or in groups. There's a real warmth to many of these that is singularly lacking in many other artistocratic portraits of the period.

Camille Silvy

I suspect Camille Silvy is not a household name, despite his obvious fame during the 19th century. After leaving his native France and establishing a thriving studio in London, he had the patronage of Queen Victoria. What's most impressive though is the range: portraits, landscapes, artistic photography. In addition to his obvious skill he clearly also possessed a lively wit (see the portraits of his father-in-law looking through a frame designed like a postage stamp and of his wife leaning through an Old Master-style frame. Meanwhile his technical proficiency can be seen in the 360 degree panorama of an eerily deserted Champs Elysees, with a ghostly Arc de Triomphe just visible in the distance. You have to bear in mind this was the mid-1800s when the photographic process was very slow. This actually makes the multiple exposure artistic works even more impressive. The real treasure though is the collection of the studio's daybooks held by the National Portrait Gallery. They provide a photographic record of every sitting during those years. They could be opened at any page and would be fascinating. As it is, we get to see a rather ghoulish "momento mori" of a recently deceased child, 2 playful self-portraits of Silvy, and a group of photographs of a (black) Lago merchant and his wife (also black and a goddaughter of the Queen) Alongside the numerous cartes-de-visites of society and theatrical personalities, it all provides an intriguing window onto Victorian society.

Irving Penn

What's most noticeable about the photographic portraits on display is how the (mostly) spartan settings focus attention so comprehensively on the figures and faces of the subjects. There are no extraneous distractions and in the early works, where full-figure shots are the norm, the body language tells all. Many of the subjects don't smile, the exceptions being some of the actors (Spencer Tracy positively twinkles while Audrey Hepburn and Grace Kelly exude Hollywood glamour). Not all though: the double portrait of the redoubtable Anna Magnani and director Roberto Rossellini feels thoroughly confrontational as their shadowed faces glower at the camera. That's the other thing. Many of the subjects stare back, unsmiling, at the viewer. They are a fascinating mix of 20th century cultural icons - artists, writers, dancers, actors, designers - and almost best of all, amid of group of Italian intellectuals in a Roman cafe out peaks the familar figure of Orson Welles, completely unexpectedly ...