david ross mcirvine • Link
As noted at Jim Bender's fine blog, Thomas Whetstone served in the Commonwealth navy.
There are some other sources on him, too
He was a nephew of Oliver Cromwell, as has mother was Catherine Cromwell.
Yet in 1659 he switched sides and swore loyalty to Charles II. He was involved in the approach to Edward Montagu, and upon the Restoration he was knighted, and will appear thereafter as Sir Thomas Whetstone.
The name also appears as "Whitstone" sometimes.
He was a privateer thereafter, in Jamaica and Cuba.
He was also made into a fictional character in a number of novels from the 1980s, which I've never read, in which he is a member of a seagoing duo.
biography here (search for his name on the page).