Who is Osmond the Mason from Sarum: The Novel of England and what is their importance?

Osmond the Mason lives in Sarum during the thirteenth century. He is married to a woman named Anna. The couple has a son, Edward, as well as two daughters. Osmond spends his life working on the cathedral at New Salisbury and is honored by being accepted into the mason's guild earlier than expected because of his great talent. Osmond is eighty years old when the cathedral is completed.