Balthazar Gerbier

As a designer of siege machinery he was recommended by Maurice of Nassau, later Prince of Orange, through whose efforts Gerbier arrived in London in 1616, in the train of the Dutch ambassador.

The king inherited Gerbier after Buckingham's assassination (1628) and employed him as resident agent in Brussels, a difficult post (1631–1641)[12] He is regarded as being a member of the "Whitehall Group" a term used by Oliver Millar in a magazine article in 1956 and subsequently in a 1958 book.

While in Brussels as the English agent, Gerbier conspired with Flemish nobles to overthrow their Spanish governors and then sold the secret of the conspiracy to the King of Spain.

His court appointment put him in contact with the Lord Treasurer, Richard Weston, 1st Earl of Portland, for whom Gerbier advised on the construction of a house and garden at Putney Park, Roehampton, Surrey, which was demolished in the eighteenth century (Colvin).

A political feud soon led to Gerbier's replacement in 1641, followed by a couple of decades during the Civil War and the Commonwealth in which he improvised a living, ventured a banking scheme in France, made a gold-hunting venture to Guiana, kept a painting academy in Bethnal Green, and allied himself to Cromwell and his republican government, with a profession of loyalty to the Parliamentarians in 1642-43[15] and a dedication to Lord Fairfax of a lecture on military architecture (1650),[5] In 1653 he published an account of the evil effects on sovereigns of wicked and pernicious favourites.

In the 1660s Gerbier's necessities induced him to advertise himself by publishing some essays on architecture: A brief Discourse concerning the Three Chief Principals of Magnificent Building (1662) and Counsel and Advise to all Builders (1663).