Surrounded by a twentieth century housing estate in south London, this classical building comes as something of a surprise. The Orangery, as it is known today, was once a feature of the pleasure grounds of Robert Thornton’s house on the edge of Clapham Common.

Thornton (1759-1826), an MP and businessman, had inherited a substantial fortune from his merchant father, John Thornton (1720-1790). Robert’s house stood in a small landscaped park with lakes, and in around 1792 he added this elegant building. Over the door is an inscription from Virgil which gives a clue as to the purpose of the fine structure: HIC VER ASSIDUUM ATQUE ALIENIS MENSIBUS AESTAS, which translates as ‘Here is eternal spring and summer in months not her own’, or ‘Tis here eternal spring and summer all the year’: the building was a greenhouse, where tender plants could be kept alive in the colder months of the year.

The artist Joseph Farington visited in 1806, with his friend William Wilberforce, and noted in his diary that the Orangery was built to a design by Dr Burgh of York. William Burgh (1741-1808) was Irish-born, but lived in York for many years. He doesn’t seem to have a history as an amateur architect, but he was a friend of the poet and garden designer William Mason, and wrote a commentary to accompany the 1783 edition of Mason’s poem The English Garden. In this text Burgh wrote that Mason’s lines about a greenhouse ‘where rare and alien plants/might safely flourish’ was inspired by the French writer and landscape designer René Louis Girardin. Girardin published De La Composition des Paysages in 1777, in which he suggested that a greenhouse with a background of trees would form a ‘jolie tableau‘. Girardin’s concept and Mason’s lines were brought to life in Clapham.

Long since lost is a marble tablet which was inside the building. It was inscribed with an extract from William Cowper’s poem The Task, including these lines which echo the quotation from Virgil on the frieze:

Unconscious of a less propitious clime,
There blooms exotic beauty, warm and snug,
While the winds whistle, and the snows descend.

The pediment is decorated with what are believed to be Coade stone ornaments. In the engraving (above) the central plaque appears to feature a profile, but if that was the case it has disappeared, and it is not known who or what it represented (by the mid-20th century the oval space was a window which lit the attic behind the pediment). The Greenhouse, as it was originally known, had a view of a serpentine canal and lawns and then over a haha to the meadows and another serpentine lake beyond. The Greenhouse was originally furnished with huge sash windows, with curious glazing between the columns – rather like stretcher bond in brickwork (see the photo’ below).

In 1808 Queen Charlotte, the Princesses and the Dukes of Cumberland and Cambridge visited the Thorntons at their ‘Clapham Villa’, and were shown the Greenhouse, but soon after Thornton got into financial difficulties. The Thornton Estate was offered for sale in 1810 when it was described as a ‘most superb villa’ with gardens full of native and exotic species ‘now in the highest state of cultivation’. The map in the sales particulars shows the ‘Greenhouse’ overlooking one of the serpentine lakes.

The estate was on the market again in 1851 when the ‘beautiful conservatory of Portland stone’ was described as ‘commanding views over the pleasure grounds and rich meadow land, which presents the appearance of a small park’.

The estate was bought by a Belgian order of nuns who established the Notre Dame convent and school on the site. New buildings were added, playing fields and tennis courts were laid out, and the girls could row on the serpentine lake and ride ponies in the grounds.

The convent closed in 1939 but its name lives on in the Notre Dame Estate, which was developed on the site of the convent and former Thornton gardens soon after the Second World War.

All that remains today of the pleasure grounds is the Orangery, which serves as an elegant backdrop to a recreation ground in the middle of the Notre Dame Estate. In the early 1950s the writer E.M. Forster, whose great-aunt Marianne was a Thornton, visited Clapham and found ‘no Thornton memorial except a dilapidated Orangery’. He was saddened that the site had been cleared ‘at a time when development was unusually ruthless’.

Unsurprisingly, the windows were the first casualty when the building stood empty, and today the rather forlorn building stands behind security fencing.

The Orangery has been largely without a purpose since the estate was constructed. Drawings by the Borough of Wandsworth Engineer, Surveyor and Architect show that the building was consolidated in 1955 when it was listed at Grade II, and it has had occasional remedial works ever since. The Orangery is on Historic England’s Buildings at Risk Register and, despite much debate and local support, a viable future for the structure remains to be found.

Update October 2025: Private Eye’s architecture correpsondent, ‘Piloti’, wrote about the orangery in the edition dated 17-30 October 2025. More than half of the roof has collapsed and Lambeth Council are seeking external funding to pay for repairs estimated to cost £100,000.

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The 18th century poet William Cowper (1731-1800) was wont to write his works al fresco in a shelter in a garden or park. His first was a tiny ‘nook’ in his garden in the town of Olney, and he later composed lines in an alcove in the park at nearby Weston Underwood. Both survive today.

From 1768 to 1786 Cowper lived at Orchard House on the market place in Olney. The little summerhouse in his garden had been built as a smoking hut by the previous owner, but it adapted easily to Cowper’s use as a writing hut, or ‘Bouderie’ as he called it in 1785. Furnished with a table and two chairs, it was ‘secure from all noise, and a refuge from intrusion’.

Cowper moved to Weston Underwood in 1786 and the Throckmorton family of Weston Underwood Hall put the gardens and park at his disposal, including the shelter called the Alcove which at that date terminated a lime avenue leading from the house.

The following year Cowper’s friend Lady Austen challenged him to write a poem with a sofa as the theme. Initially intending to compose a few lines, the work somehow turned into the six books that make up The Task.  The poem includes a description of a walk through the grounds of Weston Underwood to the Alcove and these lines are engraved on a tablet in the building.

The Alcove was built in around 1753, but by the end of the 18th century the summerhouse is said to have been abandoned after the tragic death of the man who was painting the roof. This story is recorded in Cowper, Illustrated…, published in 1803, by which date the Alcove was described as showing signs of decay.

Cowper recorded in The Task that the Alcove attracted visitors who defaced the interior with graffiti (see the text on the plaque shown above). It is ironic then that his Summerhouse in Olney became an unusual ‘visitors’ book’ after the poet’s death, with Cowper’s fans inscribing their names on the walls. In 1867, when a restoration was planned, there were fears that the work would obliterate the many ‘signatures’ on the walls, which had become accepted as an important part of the building’s history.

The last Throckmorton to live at Weston Underwood died in 1826, and the following year ‘the fine old mansion’ was pulled down. The estate was sold at the end of the century, but subsequent owners continued to allow access to Cowper acolytes, including the many who descended on Olney in 1900 to celebrate the centenary of the poet’s death. On April 25th of that year there was a ‘Public Celebration And a Holiday for Olney’, the highlight of which was the official opening of the Cowper Museum in the poet’s former home in the town. Medals were struck, and silver spoons fashioned to mark the occasion, and extra trains were laid on to accommodate Cowper’s many fans.

By October 1946 the Alcove at Weston Underwood was said to be ‘badly in need of repair’ and Lord Denham, the then owner of the Weston estate, carried out repairs early in 1947. Lord Denham also alerted the Cowper Society, which launched an appeal to recoup the £200 which had been spent on the work, but the response was slow. At the same time the Cowper Society began discussions with the National Trust and other heritage bodies. The National Trust’s representative James Lees-Milne visited Weston Underwood to see the Alcove early in 1948, but was daunted by the potential costs of keeping the building in good repair.

The Cowper Society then approached Newton Pagnell Rural District Council. It agreed that the Alcove should be preserved, but proposed that the County Council should take the lead. In June 1948 Lord Denham agreed to convey the Alcove, and a small parcel of land around it, to Buckinghamshire County Council.

The Alcove is beautifully maintained by the council, and this most idyllic of spots has full public access. The Summerhouse can be seen in the pretty garden of the gem that is the Cowper & Newton Museum in Olney (Newton was Cowper’s friend and is best remembered today for his hymn Amazing Grace) https://cowperandnewtonmuseum.org.uk

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