Complex sentence: The constituency of Berwick-upon-Tweed is in the county of Northumberland and includes as its northernmost point the town of Berwick-upon-Tweed and stretches south to include the towns of Alnwick and Amble--the Northumberland coast forms its long eastern boundary.
Split into simpler sentences: The constituency of Berwick-upon-Tweed is in the county of Northumberland. It includes as its northernmost point the town of Berwick-upon-Tweed and stretches south to include the towns of Alnwick and Amble--the Northumberland coast forms its long eastern boundary.