In 1994 the art magazine Modern Painters invited fresh blood onto its editorial board. The new intake included a novelist, William Boyd, and a rock star, David Bowie. "That’s how I got to know him," says Boyd. "We’d sit at the table with all these art critics and art experts feeling like new boys slightly having to prove ourselves. He interviewed Balthus, he interviewed Tracey Emin. He wrote for the magazine effectively."

Can a portrait really be a portrait if we can’t see a person’s face? And what if the reason we can’t see their face is that it is covered with a lump of dough? Is it a joke? And if it is a joke, is it on us or them? Or perhaps it is a joke about art itself: doughy masks aside, Dahlgaard’s portraits are in every other way conventional, and dough is not so dissimilar to clay, a venerable material in the history of art.

From weaselly shyster to spineless drip, the biographies of Goya’s subjects are often superfluous: exactly what he thought of each of his subjects is jaw-droppingly evident in each and every portrait he painted. Quite how Goya got away with it is a question that will continue to exercise his admirers indefinitely, but it is testament to his laser-like insight that he flattered his subjects enough that they either forgave or didn’t notice his damning condemnations in paint.

Some time in the late 1280s, the artist Cimabue was wandering in the Tuscan countryside when he chanced upon a boy shepherd. According to Vasari, whose Lives of the Artists is the source for most such stories, the boy was “portraying a sheep from nature on a flat and polished slab, with the stone slightly pointed, without having learnt any method of doing this from others, but only from nature.” The young untrained artist was Giotto, who would be taken to Florence as Cimabue's apprentice and soon outstrip his master.

On this dark, silent night as the world holds its breath in anticipation, everything is still but for the occasional whisper of a breeze ruffling the curtains. It is so quiet that a deer, that most nervous of creatures, has tiptoed all the way up to the window, gazing beyond us to a point further inside the room. The mirror on the dressing-table allows us to share the view into the room behind us, and there is a glimpse of a cot, the Christmas rose that hangs over it symbolising the Virgin Mary. And yet, something is wrong.

David Jones’ black and white drypoint – a drawing made by incising lines on a copper plate with a diamond-tipped needle and then printing from the plate – is a view of the nativity which is fresh, full of wonder and a highly intelligent naïveté. It shows all the sophistication of an artist who has looked at the art of the past but is also fully aware of modernism’s confusions of perspective, able to deploy them even when depicting recognisable scenes.

At first sight Piero della Francesca’s The Nativity appears to be a simple picture, especially when compared with more flamboyant depictions of the scene by artists such as Gentile de Fabriano, Botticelli and Rubens. Like a director staging a play on a limited budget, Piero has been sparing with his cast, props and scenery.

Art collectors are rarely what one might expect. Everyone has their particular enthusiasms, quirks and foibles, which make their collections unique and reflective of their tastes. In my career as a curator I have learnt never to have preconceptions when visiting collectors. The best pictures can often be found in the most modest of homes. Nothing can beat the buzz of encountering an iconic artwork in the most unlikely of settings. It is a lesson in how important it is not to make judgements about individuals before meeting them properly.

Huge canvases, bold, expressive brushwork and a full-bodied, vibrant palette. Chantal Joffe’s figurative paintings are certainly striking and seductive. Citing American painter Alice Neel and American photographer Diane Arbus as two abiding influences, Joffe’s portraits are predominantly of women and children who often convey a sense of awkwardness and social unease. As well as portraits painted from personal and family photographs, her inspiration has also come from pornography and fashion magazines.

Polo played in surplus First World War tanks; zeppelin-shooting as a gentlemanly leisure pursuit; the mighty vessel RMS Tyrannic, proud host of the Grand Ballroom Chariot Race and so safe "that she carries no insurance". These are just some of Canadian satirical writer and artist Bruce McCall’s ingenious retro-futurist creations. Slyly merging meticulous realism and madcap fantasy, they depict – with parodic faux-nostalgia – a world that never quite existed in order to comment on the one that does.