Was the contract too unreasonable to enforce?

Mason was a surgeon/apothecary in the English town of Thetford. Davis wished to apprentice himself to Mason. The two agreed that Davis would work for Mason and learn his profession. They further agreed that if Davis left Mason’s practice, he would not set up a competing establishment within 10 miles of Thetford at any time within 14 years. Davis promised to pay £200 if he violated the agreement not to compete.
Davis began working for Mason in July 1789. In August 1791, Mason dismissed Davis, claiming misconduct, though Davis denied it. Davis then established his own practice within 10 miles of Thetford. Mason sued for the £200.
Davis admitted promising to pay the money. But he claimed that the agreement should be declared illegal and unenforceable. He argued that 14 years was unreasonably long to restrict him from the town of Thetford, and that 10 miles was too great a distance. (In those days, 10 miles might take the better part of a day to travel.) He added an additional policy argument, saying that it was harmful to the public health to restrict a doctor from practicing his profession: if the people needed his service, they should have it. Finally, he said that his “consideration” was too great for this deal. In other words, it was unfair that he should pay £200 because he did not receive anything of that value from Mason.