Black Victorians, Manchester Art Gallery, Birmingham Museum and Art Gallery

When Mary Seacole, whose parents were Jamaican and Scottish, offered her services as a nurse during the Crimean war, she was rebuffed by the War Office. 'Did [they] shrink from accepting my aid because my blood flowed beneath a somewhat duskier skin than theirs?' she asked.

Undeterred, Seacole paid her own way to the battlefront and became as great a heroine to the soldiers she nursed as her white, well-to-do contemporary, Florence Nightingale. On her return to England, Seacole was fêted, awarded a medal and thanked by Queen Victoria.

The Queen's nephew, the sculptor Prince Victor of Hohenlohe-Langenburg, invited Seacole to sit at his studio in St James's Palace. A terracotta maquette of the heroic black nurse, on loan from the Institute and National Museum of Jamaica, is one of the sculptures and many images of black men and women in Black Victorians, the exhibition which was on at the Manchester Art Gallery from October last year and has now moved to the Birmingham Museum and Art Gallery until 2 April.

The War Office might have rejected Seacole's help, but it was only too happy to recruit black soldiers and sailors to fight for King or Queen and country. In Daniel Maclise's The Death of Nelson, a black sailor points to where the fatal French shot has been fired, while another offers rum to a wounded comrade near the fallen admiral. Historians estimate that there were probably 25 black sailors on the Victory that day.

The exhibition also has a study for David Wilkie's 1822 painting, Chelsea Pensioners Reading the Waterloo Despatch, commissioned by the Duke of Wellington in 1816. In the middle of the London crowd celebrating the news of victory the artist painted a black soldier from the 'first regiment of Foot Guards, a native of San Domingo'.

If you are wondering why paintings of Trafalgar and Waterloo are in an exhibition titled Black Victorians, it is because the term Victorian is used very loosely as a shorthand for the whole 19th century: so other Georgians, such as the prize-fighter Bill Richmond, get co-opted. The guest curator, Jan Marsh, admits that 'the boundaries of the show are fuzzy'.

As well as nurses, soldiers and sportsmen, the exhibition includes images of black musicians, actors, artists' models and even a bishop of the Church of England, Samuel Ajayi Crowther, who was consecrated at Canterbury in 1864. A carte-de-visite, a small photographic portrait, from the National Portrait Gallery shows him in his clerical finery.

It is the first time that such a collection has been brought together. For that alone, Marsh and the Manchester and Birmingham galleries deserve congratulations.

The exhibition opens with a striking bronze and marble bust of Othello by the Italian sculptor Pietro Calvi. It could have been intended as a posthumous tribute to the black American actor Ira Aldridge, who appeared at Manchester's Theatre Royal in 1827.

The celebrated classical actor appears in a portrait by James Northcote, a pupil of Joshua Reynolds, one of the first paintings acquired by Manchester. The portrait was the starting point for Marsh's research. Strangely, the painting and sculpture are not shown together.

Alongside oil paintings and sculpture, the exhibition includes many photographs, prints, drawings and ephemera. Combining such a wide range of media in any exhibition is difficult, especially around six different themes. Hopefully, in Birmingham the hang will be more visually coherent than it was in Manchester, which seemed unbalanced in places.

Black Victorians' strength is the way it brings to the foreground some remarkable life stories, for example, 'the willowy, handsome, light brown six footer', Arthur Wharton. He was the first black professional footballer in England, playing for Preston North End in the 1880s. The son of a Methodist minister in Accra, Wharton was sent to London as a boy to be educated.

Sarah Forbes Bonetta was also sent to Britain, but under very different circumstances. The seven-year-old was presented as a gift to a British naval commander in 1850 by an African chief in Dahomey (present day Nigeria).

She appeared at court where Queen Victoria decided to become her godmother and arrange for her education. A watercolour by Octavius Oakely shows the child in an imaginary African landscape - a remote and savage land from which she had been 'saved'.

Such personal interest was common in the royal family. The exhibition includes the portrait Muhammed, A Nubian painted by the Queen's daughter, also called Victoria. She wrote to her mother that the 24-year-old was splendid: 'I wish you could have seen him.'

The Queen herself appears in the huge painting The Secret of England's Greatness by Thomas Jones Barker. In the picture Victoria is shown presenting a large Bible to an African prince's ambassador, who gratefully receives it on bended knee.

The image was hugely popular, particularly with missionaries, and was widely reproduced as a print. The fact that the incident never took place didn't matter as it perfectly suited the Victorian's belief that they were bringing Christian light to the 'dark' continent.

In the book accompanying the exhibition, Marsh refers to the Victorian critic John Ruskin's flippant remark, 'the main purpose for which negroes must have been made was to be painted'.

The concluding section of the exhibition, Artists' Models, shows how painters loved to employ black people to sit for them. William Etty, who had an eye for a handsome male, black or white, probably recruited a boxer or soldier able to hold the energetic pose of the painting The Wrestlers.

Dante Gabriel Rossetti ruthlessly forced a young boy (who he had found in a London hotel travelling with his 'master') to sit still for him for another painting in the show, reducing the poor child to tears.

Above all, Black Victorians shows how white artists (and they are all white) painted and sculpted black people far more than is commonly imagined, and not just as slaves or servants, revealing a fascinating cast of characters in the process.

Caroline Worthington is the curator of art at York Museums Trust

Project data

Cost: £138,000

Funders: Corporate Patrons of Manchester City Galleries (Manchester Art Gallery only)

Exhibition design and lighting: In-house

External curator: Jan Marsh

Exhibition ends: Birmingham Museum, 2 April