A scarce mid 17th Century English secret.  This is an unusual piece of armour that would have been worn by a cavalry officer or such like underneath a wide brimmed felt hat to protect the skull. These flamboyant felt hats often adourned with Ostrich feathers were known as cavalier hats and were apparently worn by some of the wealthy supporters of King Charles I during the English Civil War. The cavaliers liked to dress in extravagant clothing and a Lobster tailed helmet would most probably not of suited their attire hence the secret would have been worn underneath their flamboyant hats instead to aid protection without comprimising style. There is an identical secret displayed at the Tower Armouries.