Russia is the largest country on earth, unimaginably vast. Its people naturally have a great attachment to their country – and its landscape – in spite of their turbulent history, and in the late 19^th century painters portrayed with deep feeling their native environment, their feelings for the motherland perhaps intensified among the more sophisticated the more they had travelled and studied in Europe. 

Walk up Central Park West, past the Dakota building and all those plush-looking podiatrists’ offices with their gold plaques, and just before you get to the Museum of Natural History you’ll find the New-York Historical Society and Museum at 77th Street (it also houses a great research library, open to all). Descending its steps is a life-size replica of Marcel Duchamp’s Nude Descending a Staircase (pictured below), and on the day I visited some school kids were yelling, "That’s a nude woman? What? Where? I don’t see it."

Even by his own eerie-peculiar standards, this is a perturbingly odd painting by that gifted English eccentric Stanley Spencer. It’s the night before Christmas and Christmas stockings hang from each bed frame: in this case, long rubber boots and saggy-bottomed Long Johns. And before we even consider what the occupants of each bed are up to, look closely at the heads of some of those toy figures: their painted grimaces are the thing of children’s nightmares.  

“Repellent” is one word I’ve heard to describe Alastair Adams’ new portrait of Tony Blair, but I don’t know if that’s a reaction to the painting or the subject. In either case, I can’t say I share that gut-reaction. Most of the portraits in the National Portrait Gallery manage to say very little about the subject or their reputation. This one does, so that’s my first positive response to it. 

There’s movement towards a walk after lunch, but by the time everyone’s hummed and hawed about where they might go, rubbed their bellies after one too many forcemeat balls and argued about who put the Guardian Quiz where, it’s already dark and there’s only you and one other still up for it. They cry off – a mercy – and you’re alone, heading out across the garden, along the path towards the headland. As you crest the dark bank you’re hit by freezing wind and the radiance of the moon’s path across the icy sea.

Jan Gossaert’s The Adoration of the Kings, painted in 1510-15, is a sumptuous, richly detailed and even, to us today, slightly hilarious painting. It’s the large central panel of a Flemish altarpiece which includes practically every motif of the subject possible in a heady mix of ingredients.

The term “snow day” may have been coined with the most recent spate of cold winters in mind, encapsulating the modern-day, not to mention British, consequences of winter weather, but Hendrick Avercamp’s Seventeenth-century “snow day”, painted in around 1615, is a hearty reminder that nothing changes. And just as today we tend to fall into two camps, those determined to enjoy the weather and those irritated by the disruption, Avercamp’s scene on a frozen Dutch river depicts all types, ages and temperaments.

The photographs of Henri Matisse at work show, over the years, a sober, suited, bearded and dignified figure; there is also a charming series of Matisse in a white coat, as though he were a doctor, sitting in his studio and thoughtfully examining in close-up a curvaceous naked young woman, his model. In his maturity, he looks almost like the stereotype of the upper middle class professional, the lawyer that he once almost was.

In 1997 I was in South Africa working on Truth and Lies, my book about the Truth and Reconciliation Commission, when the New York Times Magazine said that they were doing a major feature on Mandela. He’d been in office for three years. The photographs were taken in the presidential house, the former seat of the oppressors. It felt very surreal for me because even the décor was Cape Dutch furniture. It was not what you might imagine for a black president.

This exhibition makes me very sad. And not just because the subject of this long overdue survey died at the age of 28, and so left behind a body of work that stretches to only two very small galleries in the current exhibition, but because it does Pauline Boty, Pop artist and a contemporary of Peter Blake, a disservice.