King's Scholar
A King's Scholar is a foundation scholar (elected on the basis of good academic performance and usually qualifying for reduced fees) of one of certain public schools. These include Eton College, The King's School, Canterbury, The King's School, Worcester, Durham School and Westminster School, although at Westminster their name changes depending on whether the current monarch is male or female (under Elizabeth II, they are Queen's Scholars).
King's Scholars at Eton College
At Eton College, a King's Scholar (Colleger) is one who has passed the College Election examination and is awarded a Foundation Scholarship and admitted into a house, College, which is the oldest Eton house and consists solely of King's Scholars. There are, at any one time, around 70 King's Scholars, and they are distinguished by their black gowns. The other boys at the school, more than 1200 of them, are known as Oppidans.
This gown is said to be the basis of the nickname "Tugs", from the Latin "gens togata", i.e. "toga'd people", although this particular slice of Eton argot has been less often heard in recent years.