I haven't been to Buck House, but my parents went to The Queen's garden parties on a number of occasions. In 1987 our eldest girl, who was a senior Girl Guide, was among the first of the Guides to help out with one of the garden parties, which had always been the prerogative of the Scouts heretofore.
What is the hardest task you have performed? Apart from giving birth to three babies, I think building a soakaway would rank as the hardest.