[1911 Britannica] "a market town in the Wisbech parliamentary division of Cambridgeshire, England, 25z m. N. by W. of Cambridge.... It lies in the midst of the flat Fen country. The church of St Peter is principally Decorated; and there are fragments of a Benedictine convent founded in the loth century and rebuilt after fire in the first half of the 14th.... To the north runs the great Forty-foot Drain, also called Vermuyden's, after the Dutch engineer whose name is associated with the fen drainage works of the middle of the 17th century." http://www.1911encyclopedia.org/Chatteris
The overlays that highlight 17th century London features are approximate and derived from:
Open location in Google Maps: 52.454543, 0.050011
Chart showing the number of references in each month of the diary’s entries.