Carolyn Freeman Travers, Research Manager at Plimoth Patuxet Museum, wrote in an article entitled, “Were They All Shorter Back Then?” that the “average height for an early 17th-century English man was approximately 5′ 6″. For 17th-century English women, it was about 5′ ½”. While average heights in England remained virtually unchanged in the 17th and 18th centuries, American colonists grew taller.”
Note: Update to links May 2022: PDF Document from Evergreen Log, 2006: Where They All Shorter Back Then?
This post from History Hoydens provides more detail about the Georgian era.
Phys.org traces the height of an average Englishman over 2000 years.
Image from “Does Height Matter in Politics?”
Jane Austen's World 