Ikon Gallery, Birmingham Shipped as a convict to Tasmania in 1823, Thomas Bock made his name there with portraits of exceptional empathy, both of colonists and those they displaced

There is a painting in this riveting exhibition of a child in a red muslin frock with puffed sleeves and a black velvet sash. The year is 1842. She might be any Victorian sitter, posing for her portrait with hands sedately clasped in her lap. But there are signs of strain in her sweet face, the feet are bare and her dark hair is cropped. Mithina is the child’s name, and she is an Indigenous Australian from Flinders Island off the coast of Tasmania. The painter is evidently a strange figure to her.

He is Thomas Bock (c1793-1855), and quite possibly unfamiliar to us as well. For Bock was a convict artist. He started out with a considerable reputation for engraving and miniature painting in Birmingham, where he lived, and is now being brilliantly revived by the city’s Ikon Gallery. On the evidence of his fine and sensitive images, he would surely have become a celebrated portrait painter.

But in April 1823, Bock appeared at Warwickshire Assizes charged with “administering concoctions of certain herbs to Ann Yates, with the intent to cause a miscarriage”. He was a married father of five; Yates was his pregnant lover. Bock was founded guilty and sentenced to transportation for 14 years. He arrived in Hobart, the capital of Tasmania, aboard the Asia in January 1824 – there are deft sketches of the prison hull, the convicts, the sailors working, or idling, all the way through the three-month voyage – and never returned to England.

Facebook Twitter Pinterest Observatory, Domain, Sir John Franklin, Captain Crozier and Captain James Ross, RN, 1842 by Thomas Bock. Photograph: Ikon Gallery

Hobart was an imperial settlement in a new world. Founded by the British in 1804 as a penal colony, it was just beginning to acquire churches, schools, courts and the outward semblance of respectable society; a little England in Tasmania. Quick sketches show spires and Georgian houses rising up in the few dusty streets, in a landscape that had for thousands of years belonged to the Indigenous Australians, many of whom appear in Bock’s paintings.

But to begin with he was employed engraving notes for the new Bank of Van Diemen’s Land (as Europeans initially called Tasmania) and producing documentary sketches at the request of the Colonial Surgeon. These include postmortem drawings of infants who lived only a few months, deeply touching in their attempts to discover the living character of the children in their dead faces; and visual records of executed convicts. The most notorious of these was Alexander Pearce, an Irish prisoner who escaped jail several times and is alleged to have become a cannibal to survive in the wild. Bock’s drawings of his handsome head, after hanging, recall Géricault’s paintings of executed prisoners – looking so closely at the features, and with such sensitivity, that they amount to portraits.

Facebook Twitter Pinterest Thomas Bock’s Sketchbook of postmortem studies, c1835. Photograph: Courtesy Queen Victoria Museum and Art Gallery

The Ikon, not incidentally, has a parallel show in an upper gallery by the contemporary artist Edmund Clark, based on a residency at Europe’s only therapeutic prison, HMP Grendon in Buckinghamshire. Unlike Bock, Clark is unable to show prisoner’s faces; one work is a film of The Oresteia, performed by inmates in masks; another depicts them as a series of pale ghosts on spectral banners; a third shows the endless round of corridors, cell blocks and courtyards from which nobody can escape, in a looped video with official pixellations. These lives are effectively censored.

In 19th-century Hobart, however, Bock was commissioned to paint prisoners and civilians alike, and following a conditional pardon in 1832 became Tasmania’s most sought-after artist. His most extraordinary legacy is the long sequence of portraits of Indigenous Australians. The young warrior with dreadlocks, tribal markings and a brave but tense face; the old leader, wary but profoundly engaged with this strange man sitting at an easel before him; the young woman, fur wrapped around strong shoulders.

A beautiful portrait duo shows Trukanini and her husband, Wurati, quick as life and full of vitality, proud yet also palpably desperate (they have been exiled to the dwindling Indigenous Australian population on Flinders Island). Bock gives them the fullest respect in graceful watercolour. At the Ikon Gallery the two paintings hang next to each other like Victorian vignettes; they might be husband and wife above a Victorian mantelpiece.

Facebook Twitter Pinterest Untitled, Wurati (Woureddy), 1831. Photograph: © The trustees of the British Museum

And this is an extraordinary double world for the modern viewer. On the one hand, watercolours of colonial ladies in ringlets and empire waist dresses, on the other, their exact contemporaries in beads and furs, some holding harpoons or torches, as if they were all equally citizens of some polite Tasmanian Cranford.

Paper is scarce so the pictures may be small, but no less strong in their force of personality. Bock catches Sir John Franklin at a distance, the governor or Van Diemen’s Land deep in conversation in a knot of other colonialists (Franklin will later vanish on the expedition to discover the Northwest Passage). He notices the specially mischievous smile of a spear-carrying fisherman, and the keen anxiety in the intelligent face of a young Indigenous Australian woman abducted, and severely maltreated, by an English whaler. The images, one feels, often exceed the commission; Bock sees more than he is paid for.

He was a pioneer in other respects too. Some astonishingly candid chalk nudes of his second wife (with whom he had another five children; his first family were all dead by 1845) attest to Bock’s endlessly tender line. And he made stunning daguerreotypes, the first in Tasmania, of which there is a case in this show. Double portraits capture the shadows of people from the long-ago past on tiny silver plates. Bock’s subtle eye for family affinities and close relationships immediately strikes home in these intimate objects with their burnished frames.

Empathy seems to me to be his legacy. An empathy for his fellow convicts, for the desperate white men thrust into this new world; but even more for those driven out by the colonists. His portraits amount to a memorial for an indigenous people dying out even as he painted and drew them. Bock is now described as an English-Australian artist, but that doesn’t seem quite right. For the best of his work surely belongs to Australia.

• Thomas Bock is at the Ikon Gallery, Birmingham, until 11 March