Flint occurs naturally
Flint is a naturally occurring material. It occurs in bands within the chalk and, as the cliff gets washed away, the flints accummulate on the beaches; but the beach flints get rolled around and therefore they end up by being round and in the smaller version they are always referred to as cobbles.
Flint is used in a variety of ways
Flint is used in a variety of ways in building. The boulder flints come out in very irregular shapes and are normally laid in the form of random rubble. The cobble flints which are collected from the beach are normally very carefully selected so that they are not higher than three inches.
Corners are always a problem
The reason for this is that there is always a problem when you come to the corner of a wall. You normally form the corner, or the coin as it is called, of another material, normally a brick and as brick is laid in courses three inches high it is convenient therefore to lay the rows of cobbles also in courses three inches high.
Flint can also be knapped
Flint can also be knapped, that is to say broken, to show the internal face. Knapped flints can come out in a variety of ways either by using the rough shape of the flint or one can use larger flints and break the flint so the face is square, so you get squared knapped flints.
The other use of flint is the form of wall which is known colloquially as bungeroosh and is very often to be seen in boundary walls and in internal walls which are subsequently plastered. Flint has been used for hundreds of years and it is simply used because it was the material most readily available.