Above: After restoration, the Cosmati Pavement resembles its original incarnation as a show-stopping work of art devised to astound all who saw it.

Last April when Westminster Abbey hosted one of the weddings of the decade, the Duke and Duchess of Cambridge were not the only stars. The Abbey’s ancient architectural beauty shone out as William and Catherine made their way to the High Altar, framed by Purbeck marble columns. Here they stood upon another treasure, the recently restored Cosmati Pavement, an intricate mosaic of semi-precious stone and coloured glass tesserae that was laid in 1268.

The Abbey’s head conservator Vanessa Simeoni, who led the Getty Foundation partfunded project between 2008 and 2010, beams when she recalls seeing the service on television. ‘I thought the pavement looked amazing, I was really proud when I saw it. We cleaned and buffed it the night before, when everything was set out. It was nice to show it off to the world.’ Even Catherine’s high heels and Prince William’s spurs didn’t cause her to wince. ‘We conserved and stabilised the pavement so it could be used for services. Generally if we had high heels on it every day I’d be concerned, but just for so few events during the year it’s not a problem.’

Westminster Abbey

Above: The present Westminster Abbey was begun by King Henry III in 1245 but has been Britain’s coronation church since 1066, witnessing the crowning of William the Conqueror, Elizabeth I, Victoria and Queen Elizabeth II – at her coronation service, the Cosmati Pavement was covered with a thick cream carpet.

In 1999, when Vanessa joined the Abbey, it was a very different story. The Cosmati Pavement was covered in ugly brown carpet that would tug off a fragile tesserae or two whenever it was lifted. Along with missing glass and stone tesserae, the colours of the pavement had become distorted under the layers of polish and dirt. Areas of the Purbeck marble framework had eroded, and most noticeably there was an ugly patchwork of ‘treacly black’ cement repairs from the late 19th and 20th centuries covering up missing tesserae, cracks and damage.

A pattern of purple and green porphyry and yellow limestone; Head conservator, Vanessa Simeoni repairs a tomb lid

Above (left-right): A pattern to be seen in the pavement, comprising purple and green porphyry and yellow limestone; Head conservator, Vanessa Simeoni repairs the tomb lid of Abbot Richard de Ware, the 13th century cleric who brought Cosmati work to the abbey.

Glorious intentions

‘Back in the 13th century the stones were chosen for their ability to take a polish and in candlelight the High Altar would have been alive with colour and have filled people with awe,’ says Vanessa.

‘Cosmati work was hugely fashionable in Italy in the 12th and 13th centuries and Abbot Richard de Ware had seen it at the Pope’s summer residence outside Rome. In Rome itself, almost every church you walk into you’ll see Cosmati floors and tombs with Cosmatesque decoration.’

Wanting a spectacular centrepiece for the Abbey and to reflect glory on King Henry III, Abbot de Ware commissioned a pavement from the Italian architect Odoricus. He and his craftsmen came to England in 1268 and brought with them a supply of stone, recycled from ancient Roman ruins, to cut into tesserae. ‘In the pavement are marbles and colourful limestones from all corners of the Roman empire – green porphyry from Greece, purple porphyry from Egypt, and travertine from Turkey – chosen for their beauty, colour and figure.’ Green porphyry in particular has small crosses within the stone, which gives it Christian connotations.

The unusual use of glass in a floor makes the Cosmati Pavement special, and uniquely its framework is made of dark grey Purbeck marble, not the typical snowy Carrara marble of Italy. ‘Purbeck marble is a truly English stone and would have been worked by English craftsmen, in collaboration with Italian craftsmen who cut the tesserae. They were all men at the top of their trade who knew their materials so well,’ says Vanessa. ‘For me it is one of the finest examples of Cosmati work in the world – it’s so intricate and well made, and we’re so lucky that there’s been comparatively little restoration.’

The central roundel is an exquisite travertine, Alabastro Fiorito

Above: The central roundel is an exquisite travertine, Alabastro Fiorito, sourced from Pamukkale in Turkey.

Eye for detail

But to stabilise the pavement enough so that it could come out from under its covering, work was needed. After several years of research and plenty of preparation, which included a photogrammetric survey, the very first task was cleaning – a delicate process which took Vanessa and conservators Paula Rosser and Ned Schärer eight months to complete, on hands and knees.

‘A build-up of wax, polish, dirt and dust had become a brown mass, which in a way unified the pavement,’ explains Vanessa. ‘We devised a technique to remove this gunk, a solvent held in paper pulp made into a poultice. Depending on the degree of soiling we’d leave it on for 20 to 60 minutes, then with swabs and brushes take it all up. Then we’d do it all over again!’

Next came the removal of the ugly cement patches, the conservators and visiting conservation students from the City & Guilds of London Art School chipping away with tiny chisels. ‘Fortunately the patching was such shoddy workmanship that in most cases we were able to uncover the original lime mortar beds that still had the impressions of where the missing tesserae had been,’ comments Vanessa. In collaboration with earth scientist, Dr Ruth Siddall of University College London, cements and mortars were analysed to ensure exactly the right medieval lime mortar mix – cleverly cut with brick dust to make it waterproof – was reapplied.

Conservator Ned Schärer beds new tesserae into lime mortar; the patterns are traditional Cosmatesque

Above (left-right): Conservator Ned Schärer beds new tesserae into lime mortar, made to the original medieval recipe which used brick dust as a waterproofing agent; the patterns are traditional Cosmatesque – roundels and figures of eight – and feature the signature combination of yellow limestone and green and purple porphyry.

To reintroduce lost or damaged stone, Vanessa sourced new Purbeck marble from Dorset, which was chiselled and honed into shape by the abbey’s two in-house stonemasons, Mark Croll and Joe Goodbody. Tracking down a new supply of porphyry was not quite so simple. ‘We had to be sure of the provenance and in the end got it from Rome, from the company that had supplied the Opificio delle Pietre Dure in Florence. We had quite a few kilos of it shipped over in a big drum.’ In the hands of master stonemason Mathias Garn and his team based in York, the chunks of brown stone transformed into beautifully cut and polished purple and green tesserae that revealed their different marks and inclusions.

For the reintroduction of glass tesserae, opaque glass was sourced in Italy and transparent glass from the Stained Glass Conservation Department at Canterbury Cathedral matched to tiny fragments of red, amber and blue glass that remained in the pavement. The team also went on a half-day course to learn medieval glass cutting techniques, taught by head of the Canterbury studio, Leonie Seliger, who also made them a medieval grozing iron to cut tesserae back at the abbey.

The final task was to treat the pavement with toned and tinted microcrystalline mineral wax. ‘Beeswax never hardens, but this does and when buffed up gives a really nice sheen,’ explains Vanessa. Gleaming once again, the Cosmati Pavement is vacuumed twice a week and buffed up weekly with anti-static cloths. After each service Vanessa notes down any changes or scratches that may occur, never tiring of the work of art she has come to know so well. ‘This is such a survivor and the craftsmanship is astoundingly beautiful,’ she says, as she treads barefoot and lightly across the floor.

Waxing the pavement to protect it; The Duke and Duchess of Cambridge exchange vows, standing on the Cosmati Pavement

Above (left-right): Waxing the pavement to protect it and provide it with a beautiful sheen was a huge job – here head conservator, Vanessa Simeoni, carefully applies microcrystalline wax with a brush; The Duke and Duchess of Cambridge exchange vows, standing on the Cosmati Pavement. Vanessa Simeoni says, ‘The pavement is beautiful when we have a service here, but it is at its most exquisite in the early morning or early evening when the crowds have gone and you get a real sense of the mass of this building’.

A few facts about the Cosmati Pavement at Westminster Abbey

  • The Westminster Abbey Cosmati Pavement (pronounced Cosmarti) is one of only three such pavements in Britain and the best preserved. The second is also at the abbey, but so fragile that it is covered over, and the third is a fragment around the shrine of martyr Thomas Becket at Canterbury Cathedral in Kent.
  • The pavement measures 24 feet and 10 inches square, and is made up of more than 50,000 individual tesserae, many of which are original.
  • Thirty-eight monarchs have been crowned in the Coronation Theatre, an area of the abbey that includes the High Altar and Cosmati Pavement.
  • A 15th century monk made notes of the pavement’s inscriptions, which have since worn away, leaving a record of who laid the pavement, when and what it represents.
  • Abbot de Ware, who commissioned the pavement, is laid to rest to the left hand side as you face the High Altar; his successor Abbot Walter de Wenlok lies on the right.
  • The pavement has had three previous documented restorations: in the late 17th century and the early 18th century when some porphyry was substituted with other stones such as serpentinite; and in the 1870s, when Sir George Gilbert Scott carefully repaired damage caused by a heavy Baroque altarpiece.

Westminster Abbey opens to visitors at 9.30am Monday to Saturday; check website for closing times. For details go to westminster-abbey.org. Vanessa gives lectures to interested groups.