Complex sentence: He opened a day school in his vicarage, and in 1848, he started St Nicholas' School, which took boarders, and was in 1849 merged to form the College of St Mary and St Nicholas, and these eventually formed the present day Lancing College.
Split into simpler sentences: He opened a day school in his vicarage, and in 1848 he started St Nicholas' School, which took boarders. This was merged in 1849 merged to form the College of St Mary and St Nicholas, which eventually formed the present day Lancing College.