Very little is known of Stefan's career, however he was mentioned as a gentleman of Moravia, and subject of Bohemia, in a letter from the Regent of the Netherlands to Henry VIII in 1544.
[2] He seems to have first offered his services as armourer and architect to Henry VIII in 1535; giving a note to the Duke of Suffolk to pass to Thomas Cromwell and the King.
[3] Stefan was part of the design team for the Device Forts at Sandgate and Camber Castles, and the gun emplacements made of earth on the Downs.
The French ambassador in London, Charles de Marillac, heard of this and reported to Francis I of France that the "German" engineer had gone to design new bulwarks.
[7] Stefan may have been the military engineer mentioned by Eustace Chapuys as returning to the Scottish border in January 1542 after having planned and commenced a line of defences.
Stefan said the Scots had made an offer to the uncle of Hans, a German plumber working at Hull, and he hoped Carne would write to Henry VIII in his favour if he found out more information.
[11] The last letter included a woodcut picture of a coin; and another of a combined horse and windmill, titled, "Eine wunderlicte roswintmulle, Emden, 1545".
On 9 January 1547, the Imperial ambassador in London, François van der Delft, wrote to Mary of Austria to ask what he should do about Haschenperg.
Stefan produced a map and subsequently six bulwarks were built as part of a larger project devised by Henry VIII.
He immediately complained to the Privy Council about the mismanagement of the works and the behaviour of Sir Thomas Wentworth, Captain of the Castle.
He thought its three artillery platforms were vulnerable to attack because "it flanketh not itselffe very well, ... and the cownter skarffe serveth to cover the approach of the enemies."
The platforms for mounting the guns were made of timber and decayed, so Knollys suggested filling the masonry walls with earth.