It is tradition, at Balmoral, for the Queen to thank the staff by laying on a ball for the estate staff and servants and this is called the Ghillie's Ball. She actually holds two, as two sets of staff change over after four weeks but that is irrelevant.
The dress code is formal, long dresses for the women and smart suits for the men, although I think I remember some people in tweed and the attending army guarding the queen would turn up in kilts... mmm kilts.. I digress, I am dredging my memory back a number of years, but I think the ball would take place after dinner (which was not a heavy affair, especially with the dancing) and while drinking was permitted, you were expected to not get drunk.
The Royal family would dance with senior members of the staff to open, but my favourite dance that I recall so clearly was The Dashing White Sergeant, although whip the willow and the eightsome reel were also good. Why, you ask this dance, well myself and a friend along with a male colleague formed one line and opposite us came Prince Charles, Prince Andrew and the Queen Mother (who was sprightly and very fit back in the day), the dancers swept around the floor changing partners and paired off. It is a memory I will never forget, and even now it seems just like a dream.
Many dances later, we were hot and bothered, the Royal family mostly had departed leaving the staff alone, but the younger ones stayed behind until the end, if you didn't know country or scottish dancing before you came, by the end of one season at Balmoral you became an expert as they were regular occurences but the Ghillie's ball was the highlight of the stay for every one of us as the traditions were upheld that we were one big family despite the upstairs, downstairs of normal day life.
ps. Black Watch kilts are my personal favourite, but they were there the first year I was and proved that a scottish kilt wearer wore nothing under the kilt but bareskin lol.