“Very flat, Norfolk”. (Noel Coward. Private Lives)
“No place in England was further away from good building stone”. (Stefan Muthesius )
“The geology of Norfolk in eastern England largely consists of … sedimentary rocks of marine origin…” 
These three statements are, of course, related. Much of Norfolk is based on chalk derived from the skeletons of countless marine organisms that rained down upon the seabed some 60-95 million years ago when the sea level was much higher. In places, these layers of chalk are 300 metres (1000 feet) deep . Quarry stone is therefore hard to find.
To build Norwich Cathedral the Normans brought in limestone from Caen in Normandy. Pulls Ferry (below), which was built later, is the medieval watergate that marks the route by which the stone was diverted from the River Wensum to the building site. However, despite this logistical triumph the core of the cathedral was still based on flint for the ashlar limestone is just a facing [2A].
Flint and chalk are found together. Skeletons of some marine organisms provided the calcium carbonate that formed the chalk strata: others – like this diatom – provided the silicon dioxide (silica) from which the nodules of flint were formed. I estimate this diatom to be ca. 15-20 millionths of a metre in diameter, giving some idea of the staggering number of organisms required just to make one flint nodule, let alone the blizzard of marine life needed to deposit 300 metre layers of chalk.
It is thought that holes formed by sea creatures burrowing through the gelatinous ooze at the bottom of the seabed provided the right sort of chemical environment for dissolved silicon – released from exoskeletons – to recrystallise, growing the irregular flint nodules around the holes .
In a wonderful piece of inorganic chemistry in action, this metamorphosis of sludge on the seabed produced flint nodules; their ‘organic’ shapes fascinated C20th artists – as did the holes. In the 1930s, Ben Nicholson, Henry Moore and Barbara Hepworth holidayed at Happisburgh on the Norfolk coast . In 1931, apparently based on the Happisburgh flints, Barbara Hepworth created one of the first sculptures with a hole through it for non-representational purposes (Pierced Form. Lost in the war). And Henry Moore’s sculptures are famously “lumpy and bumpy and sometimes have holes right through them.”
One idea why there are so many round-towered flint churches in East Anglia is that the lack of stone to make the quoins or cornerstones meant it was easier (and cheaper) to build circular towers from knobbly flints set in mortar  . Another idea is that the Anglo-Saxons introduced round towers as protection against the Danes but this seems to have been discredited by the finding that many towers are post-Norman Conquest . Geology does seem to provide the answer for while continental invaders spread far further than Norfolk only five round tower churches escaped the confines of the East Anglian chalklands compared to the 126 made in Norfolk .
Norwich had one church for every week of the year and one pub for every day.
The actual number of churches appears to have been about 57, of which 31 are still in existence. I haven’t yet visited all the medieval churches but would guess that virtually all are built of flint – even the stone-clad St Peter Mancroft contains flint. However, not many of Norwich’s churches are round-towered. One was St Benedict’s church but this was bombed in the Baedecker raids of 1942 and only the tower, which is made of unknapped flint, survives.Well shaped flints occur on Norwich’s Guildhall, which is “the largest surviving medieval civic building in the country after London“. It was built as a result of a royal charter of 1404 that gave the city the right of self-government. The east end (below) – rebuilt in the C16th with a clock turret added in the C19th – is a glorious example of diaper flushwork, where alternating diamonds of dark flint and light limestone form a smooth (i.e., ‘flush’) surface. The black and white chequerboard pattern may be a reference to the Guildhall’s use as an exchequer  in which a squared cloth was used for counting money.
In places, the Guildhall walls contain unshaped stones surrounded by shims of flint – a byproduct of knapping. Pushing flakes into the spaces around the flints – or galleting – filled the gaps and protected the exposed mortar. The selection of flints that would leave large gaps seems to have been deliberate since it allowed swirls of galleting to become a decorative feature in its own right.
By contrast, parts of the east wall have been expertly squared up. Not only was the external face of these flints made smooth but four other sides were also square-knapped with such skill that the flints could be laid in regular courses without the need for galleting or, indeed, any visible mortar.
Another civic building famous for the quality of its square-knapped wall is the Bridewell, which was built about 1370 as a private house and became a prison for minor offenders nearly 200 years later. It was named after St Bride’s Well, the first such institution in London.
The north wall of the Norwich Bridewell has claim to being “the finest specimen of faced flint work in the country” . But the knappers seem to have been less constrained here by a requirement for perfect squareness. The square-knapping is not as precise as on parts of the Guildhall and the flints are of variable size. But this honesty with which a difficult material has been handled contributes to the beauty of the wall.Flushwork was a speciality of Norfolk and Suffolk and was at its most inventive during the Perpendicular Period (1330-1530) [7, 10]. St Michael (often contracted to St Miles) Coslany is a famously exuberant example. The artist John Sell Cotman claimed that the flushwork on the south side was “one of the finest examples of flint work in the kingdom” . Parts of the church were rebuilt in the C19th. Here on the east end, restored in the 1880s, the flushwork mimics the tracery in the Perpendicular-style window next to it. This fits the general rule that representational designs were made in stone with flint in-fills while non-representational examples were in flint on a stone background .
The church of St Andrew in St Andrew’s Street, Norwich, was completely rebuilt in 1506. It also has tracery flushwork but just as fascinating is the re-set frieze of shields beneath the chancel window – the only survivor from the previous church . These can be easily examined as you trudge up St Andrew’s Hill after leaving Cinema City. Kent and Stephenson  devoted an entire chapter to this frieze. Three of the thirteen shields (below) represent: the arms of Bishop Dispenser; Richard Fitzalan the Earl of Arundel; and possibly Thomas Mowbray who was later to become Duke of Norfolk.
According to Stephen Hart  “the earliest positively datable example” of flushwork is on St Ethelbert’s gate of Norwich Cathedral (1316). The date is known with some certainty because of the events surrounding its construction. In 1272, conflicts between the cathedral and the citizens led to the torching of the Anglo-Saxon church of St Ethelbert together with the main gate to the monastery. Thirteen citizens were killed in the riots and thirty rioters were hanged . (The man fighting a dragon in the spandrels above the gate may refer to this conflict – see 13A). The king decreed that the citizens should rebuild St Ethelbert’s gate. In 1815 this C14th gateway was restored by William Wilkins [7, 11] but although he generally followed the original pattern of three circular motifs Wilkins made significant changes to the flushwork. These circles are referred to as replica ‘rose windows’  or ‘flushwork wheels’ [13A].Another decorative technique, proudwork, was in contrast to the flatness of flushwork . St Gregory’s provides a rare example in Norwich. In this case, the ashlar in tracery design stands proud of the flint.
It should not be surprising that Norwich, as a major centre of East Anglian flint-building, had its own brand of flushwork. In the Norwich style , vertical stone strips divided the flintwork beneath parapet crenellations into zones into which stone motifs were inset. This can be seen on the tower of St Clement’s Church in Colegate (near Fye Bridge), on which lozenges are decorated with blank shields indicating that God is shielding the building. The smaller lozenges appear to be recent restorations.
In serial flushwork, letters or motifs are repeated in a frieze. A good example can be found at All Saints, East Tuddenham – a few miles west of Norwich. Above the porch is the inscription in Lombardic script (Italian lettering of the early Middle Ages): GLORIATIBITR (Gloria Tibi Trinitas, or ‘Glory be to you Oh Trinity’ ). The letters are crowned when referring to god, saints and martyrs but never donors .
Seen here on the porch of St Michael at Plea (below) the Norwich workshop gave St Michael a crowned M as well as a crowned sword. The crowned sword can be seen following the first M but “over-zealous pointing” seems to have obliterated subsequent swords .
In 1671 the diarist John Evelyn wrote that Sir Thomas Browne of Norwich had told him that “they had lost the art of squaring the flints, in which they so much once excell’d, and of which the churches, best houses, and walls, are built...”. The quality of the Victorian restoration at the east end of St Miles Coslany provided one example that the art of square knapping had not been lost; this men’s lavatory of 1892 is another – an example of a different kind of flushwork.
- Muthesius, Stefan. (1984). Norwich in the Nineteenth Century. Ed, C. Berringer. Chapter 4, pp94-117.
- https://en.wikipedia.org/wiki/Geology_of_Norfolk [Ref 2A. http://nhbg.org.uk/getmedia/952a6b94-eced-411a-bb63-b508d00f6220/Newsletter-No-23-web.aspx].
- http://www.museums.norfolk.gov.uk/view/NCC081889. This links to excellent notes by Nicholas Thornton on an exhibition held in Norwich Castle Museum and Art Gallery, in 2009: Moore/Hepworth/Nicholson. A nest of gentle artists in the 1930s.
- Round Tower Churches Society. http://www.roundtowers.org.uk/about-round-tower-churches/
- Hart, Stephen. 2000. Flint Architecture of East Anglia. Giles de la Mare Pub Ltd.
- Talbot, Margaret. 2004. Medieval Flushwork of East Anglia and its Symbolism. Poppyland Publishing.
- Kent, Arnold and Stephenson, Andrew. (1948). Norwich Inheritance. Pub: Jarrold and Sons Ltd., Norwich.
- https://norwichchurches.files.wordpress.com/2016/06/st-ethelberts-chapel-and-the-riots-of-1272.pdf. [Ref 13A Summers, Dominic John (2011) Norfolk Church Towers of the Later Middle Ages. PhD UEA].
- Britton, John (1816). The History and Antiquities of the See and Cathedral of Norwich. Pub: Longman et al. London.
- Blatchly, John and Northeast, Peter (2005). Decoding Flint Flushwork on Suffolk and Norfolk Churches.
Thanks to Jonathan Plunkett for permission to use an image from the George Plunkett archive http://www.georgeplunkett.co.uk. I also thank the Norfolk Heritage Centre for their help.