The founder of the family, Luigi Tomaselli, was decorated with the title of Knight in 1113 by the Margravine Matilda of Tuscany after having distinguished himself in the battles against Henry IV, Holy Roman Emperor, who was an enemy of Pope Gregory VII, in 1092.
Giacomo Tomaselli, a noted lawyer closely linked to the ruling House of Sforza, was appointed Grand Chancellor of the Duchy of Milan in 1537.
In the late seventeenth century, the Tomaselli family were sent by the Republic of Venice to the Province of Bergamo, under the rule of Doge Silvestro Valier, to control the Venetian possessions that surrounded the river Serio.
Luigi Sergio Tomaselli, already blazoned and enrolled in the nobility of Bergamo, was awarded the hereditary title of Conte di Sottocasa by Francis II, Holy Roman Emperor in 1801[citation needed],[circular reference] that is inherited only by the principle of primogeniture.
[4][5] One prominent member of this branch of the family is historian Sylvana Tomaselli, the wife of George Windsor, Earl of St Andrews, and daughter-in-law of Prince Edward, Duke of Kent.