This is a painting by Frans Hals a dutch artist. It depicts a meeting of officers and NCOs of the security detail. A 1633 Frans Hals painting in the Frans Hals Museum, Haarlem.
This lovely card was sent to me by Laury. She says that this is a typical dutch painting from the 17th Century. The man shown at the bottom of the picture is Colonnel Yohan Claese Loo. This painting it seems was an inspiration for a self-portrait by William Merritt Chase.