You will be given a definition of a task first, then some input of the task.
In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.

Passage: The main road going through Wanstead is the A12 and was the site of a Roman villa, whilst Wanstead Manor was a Saxon and Norman manor. It formed part of the Municipal Borough of Wanstead and Woodford in Essex from 1937 until 1965, when Greater London was created. The area has a largely suburban feel, containing open grasslands such as Wanstead Flats, and the woodland of Wanstead Park, part of Epping Forest. The park, with artificial lakes, was formerly part of the estate of a large stately home Wanstead House, built by Richard Child, 1st Earl Tylney, one of the finest Palladian mansions in Britain and the architectural inspiration for Mansion House, London. It was subsequently demolished to pay the gambling debts of a relation of the Duke of Wellington.
 Link Information: Wanstead House was a mansion built to replace the earlier Wanstead Hall. It was commissioned in 1715, completed in 1722  Question: When was the estate home built by Richard Child constructed?
Output:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Answer: 1722