The stretch of the River Thames that flows alongside the Berkshire village of Cookham is renowned for its beauty. It has inspired some of the best-loved works of English literature – Kenneth Grahame's 1908 Wind in the Willows was written in Cookham Dean – and attracted boaters, walkers, and of course, artists. This was the Thames that the British painter Stanley Spencer knew in his youth, as he grew up in Cookham in the 1890s and 1900s. He painted and drew the river many times, and it features in some of his greatest works.

In his lively drawing Month of June: Going on the River, a group of holidaymakers wrestle a mattress, cushions and a hamper into a punt in preparation for an outing.

The boathouse from which they embark can also be seen, in a quieter moment, in his painting View from Cookham Bridge.

This painting shows the river in a rare moment of peace. More often, during the summer months, it was crowded with day trippers who came by train from London to Cookham and nearby Maidenhead to enjoy boating, walks and picnics. Edward John Gregory's oil study for Boulter's Lock, Sunday Afternoon captures the scene on one such busy weekend, packed with boats, skiffs and steam launches that jostle together and threaten to tip their passengers into the water.

Study for 'Boulter's Lock, Sunday Afternoon'

The biggest event in the village's social calendar was Cookham Regatta, which took place at the end of Ascot week every June. Thousands of smartly dressed visitors descended on the village for a day of waterborne festivities. Punting and rowing races were followed by an illuminated procession of boats and a floating Grand Evening Concert, when musicians played from the old horse ferry barge.

As a child, Stanley Spencer watched the Regatta from the riverbank with his brother Gilbert and sister Annie. The brothers recalled the excitement of the races, the thrill of seeing the 'swells' down from London, and the fairytale atmosphere of the evening concert. Nearly half a century later, Stanley's childhood memories would inspire his last, great imaginative painting, Christ Preaching at Cookham Regatta.

This ambitious work occupied Spencer's thoughts and energies for the last decade of his life. Unfinished at his death, it is now the focus of an exhibition, 'That Marvellous Atmosphere: Stanley Spencer and Cookham Regatta', at the Stanley Spencer Gallery, Cookham. This small gallery, dedicated to the artist's work, is housed in the former Wesleyan chapel where he worshipped as a child, and only a stone's throw from where the painting is set. The exhibition displays the painting alongside preparatory studies and related works that bring to life the heyday of Cookham Regatta, and explore the making and meaning of his final masterpiece.

'That Marvellous Atmosphere: Stanley Spencer and Cookham Regatta' at the Stanley Spencer Gallery

For several decades, Spencer had been experimenting with ideas for a painting of Christ preaching from a boat. It was based on the biblical story in which Christ, pressed upon by crowds, pushes out into a boat on Lake Galilee from which he preaches to the people on shore. An early drawing shows Christ standing stiffly in the foreground, the dove of the Holy Spirit perched on his head.

Study for 'Christ Preaching at Cookham Regatta'

It was not until around 1951 that Spencer had the idea of setting the biblical scene at the Regatta's Grand Evening Concert. In place of the musicians, Christ preaches from the horse ferry barge, surrounded by the regatta-goers who listen from their punts and the lawn of the Ferry Hotel. Spencer began to develop the subject in earnest, and soon became so enthused that he stayed up until four o'clock in the morning drawing out his ideas. By March 1953, he had amassed over a hundred drawings of different figures and groups.

Study for 'Christ Preaching at Cookham Regatta: The Elders'

Overwhelmed by the magnitude of the task, Spencer decided that 'I will have to do it in bits', and began working instead on a series of smaller Regatta paintings. Some of these are replicated scenes from the main painting. Others, such as Dinner on the Hotel Lawn, imagined episodes that could not be accommodated in the main canvas.

Early in 1954, Spencer drew the composition for the principal picture onto a huge canvas, over two metres high by five metres wide. He transferred his drawings through a combination of 'squaring up' and enlarging, and tracing directly from life-size drawings.

Beginning at centre-top, he painted section by section using very fine brushes. The canvas was rolled up in his makeshift bedroom-studio, with only the section he was working on visible at any one time. Visitors to his home found him perched on a stool balanced on top of a trestle table to reach the upper section.

Stanley Spencer at work on 'Christ Preaching at Cookham Regatta', 1957

Spencer intended the painting to convey Christ's love for the world, through his own love for Cookham. As he explained to his daughter Unity, 'Everything will be fulfilled in the symbol of the Regatta. The complete worshipfulness and lovableness of everything to do with love is meant in this Regatta scene. In that marvellous atmosphere nothing can go wrong.'

Spencer envisaged Christ Preaching at Cookham Regatta as part of an extensive series of paintings intended for his Church House or 'Church of Me'. This was a largely imaginary project of a chapel hung with biblical paintings of Cookham and the people who had played an important role in his life. Christ Preaching at Cookham Regatta was to be the altarpiece of the river aisle, while his great painting of his early career, The Resurrection, Cookham, was to hang as the altarpiece of the central aisle.

Despite its importance, Spencer made slow progress on Christ Preaching at Cookham Regatta, partly because it competed with other paintings for his time. From 1950, he experienced a new wave of success in his career. He was awarded a CBE, re-elected to the Royal Academy, and exhibited his paintings to great acclaim. As a result, he received many commissions for portraits and landscape paintings, like Englefield House, Cookham, commissioned by a local patron, Gerald Shiel. Such paintings brought him financial stability but distracted him from the imaginative paintings that he felt were his 'real' work.

Progress was also hindered by Spencer's own failing health. In December 1958, he was operated on for cancer and afterwards spent several weeks recovering at Cookham vicarage, staying with his friends, Reverend Michael and Rachel Westropp. While there, he painted Rachel's portrait as a birthday present for her husband.

The rolled-up canvas of Christ Preaching at Cookham Regatta also came to the vicarage, and Spencer resumed work as soon as he was able. He was determined to finish it, writing to his friend Mary Behrend, 'I am not all that wealthy but I cannot tempt fate any further, all this putting off of this & that … I love and long to paint … I am thankful I have been at least allowed the good health to paint that further bit of the old man with the oars & the mop.'

Detail of 'Christ Preaching at Cookham Regatta' with boatman and mop

Over the next few months, he painted in further sections, completing the figures of the landlord and landlady of the Ferry Hotel. Spencer reportedly said that the landlord, who surveys the crowds with his hands in his pockets, was thinking about how much money he would make from them!

Detail of 'Christ Preaching at Cookham Regatta' with landlord and landlady

Sadly, Spencer never fully recovered, and his self-portrait drawn later that year is a brutally honest portrayal of ageing and ill health.

A few months later, his cancer returned. By the time Spencer died on 14th December 1959, he had managed to complete three-fifths of Christ Preaching at Cookham Regatta. The unfinished painting was purchased by his patron, Lord Astor, and displayed in a prominent position at the 1960 Royal Academy Summer Exhibition, where it was hailed as 'the epitaph of Genius'.

'That Marvellous Atmosphere: Stanley Spencer and Cookham Regatta' is at the Stanley Spencer Gallery until 2nd November 2025.

Amy Lim, curator, Stanley Spencer Gallery