Flint is, after brick, the most widespread and typical of all East Anglian wall building materials. Flintwork comes in various degrees of workmanship and finish. At the simpler end is pebble construction. This kind of structure is found round the coast where pebbles occur naturally on the beach. Pebbles are very hard, as any that are easily broken are soon reduced to sand by the ceaseless action of the waves. Only the hardest stones stand up to constant abrasion of the sea to produce pebbles. Inland the flints appear as broken stones, having a natural ‘face’ without any additional work being done.. Nowadays expensive properties may be built of pebbles in the belief that they are imitating local buildings of years gone by; but unless they are near the coast they are wrong. Inland these builders should be using flints, which having broken facets produce a very different looking structure.
Within this general description of pebbles there are different types of construction. Starting at the simpler end there is the “random” pebble wall. This is not as common as you might expect; in fact truly random pebble walling does not exist. There has always been some selection made, so that neither the very small stones nor the very largest are used. This type of stone-work is referred to as rubble. Continuing to greater complexity of construction the pebbles are graded closely as to size and to some extent to colour as well. These pebbles are be set in courses, with stones of the same size alongside each other. but each course would use a different size.
We now leave pebbles and progress to the the next kind of flint building. This has faceted flints. They can be left as found, in the size and shape they came in; this again is referred to as rubble construction, only the outer face is more or less flat. Normally some work is done on these stones before they are laid, in much the same way as we mentioned earlier with regard to pebble. With these flints however they are struck hard with a hammer or “knapped”, to produce a flat surface. Even without further working on the stones some very fine buildings can be produced using knapped flints if some thought is taken in placing them to make the mortar courses as thin and inconspicuous as possible. The art of knapping flint for buildings has been lost entirely.
Lastly we come to squared flints. These are struck in five planes to produce completely regular courses. The squared stones are laid in a similar way to bricks. Once again they can be selected so that the stones in each course are of the same width, but adjacent courses may be of a different size; or at its most developed stage a whole section of wall may be produced of matching stones. The mortar courses which are naturally thin in this type of construction are often made thinner still by the process known as galleting. Here the mortar course is made less obtrusive by the insertion of flakes of flint. There is a fine wall of galleted flint at the Bridewell in Norwich. (Galleting is also found in carstone walling, where the flakes used are of carstone.)
An even more delicate form of flintwork is found late medieval ecclesiastical architecture where the tracery in the windows is reproduced in flint and freestone walls. A fine example of this is seen at St Miles (Michael’s) Coslany in Norwich. Flint requires the use of some other building material (freestone or brick) to create the corners and window openings. The only shape which lends itself to the exclusive use of flint is a circular structure, which accounts for the many round church towers in Norfolk.