Complex sentence: This was largely due to the last remaining clay reserve having been exhausted meaning that in order to carry on producing bricks the Ashbys would have to relocate to Swanwick where there was an abundance of clay.
Split into simpler sentences: This was largely due to the last remaining clay reserve having been exhausted meaning that in order to carry on producing bricks. The Ashby family had to relocate to Swanwick where there was an abundance of clay.