It is believed that a place of worship was erected on the site of St. Mary's church during the 7th century AD. This would have been a wooden structure and was replaced with a small Norman stone church in the 12th century, essentially the core, or nave, of what can be seen today and measured 66 feet by 21 feet. At this time the church was presented to Reading Abbey. This was gradually extended with a chancel in the 13th century followed by the lower half of the church tower in the 14th century. It is believed bells were first added in the 16th century.
In the 1850s the entire church was renovated with most parts such as the Danvers Chapel being covered in flint. The church was also known for a period as St. Luke’s and indeed there is a carving of St. Luke on the pulpit. However it is commonly believed it was originally known as St Mary’s and by the early 1880s it had reverted to back to St Mary’s. The Church has many of Thatchams residents buried in it including Francis Baily who had been offered burial at Westminster Abbey.
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