They travelled all over europe, and many of them crossed the north sea to britain. Just to the east of where I live, the town of Kingston upon Hull (better known just as 'Hull') became Britain's first all-brick town, even its defensive walls were of brick. Just as Max said all the bricks were made on site. Hull sits at the northern shore of the Humber estuary, on a rich bed of secondary clay. There's nowhere nearby to quarry stone.