Rosie, from Stanford Dingley, Berks, who was number A269 in the queue, was one of the youngest there – and was following in the footsteps of her grandfather Edward, 77.
At the same age as Rosie, Edward camped out on the streets of the capital before the Coronation in June 1953.
Rosie’s mother, retired Army Major Aisling Bucknell, 45, got permission from her daughter’s school to bring her to London.
Rosie said: “I think it is good if we say goodbye to the Queen before she goes up to heaven. When we go into where she is, we will pay our respects.”
Iraq veteran Aisling said: “It has all been organised brilliantly and the atmosphere here is very relaxed, everyone’s getting along well.”
Of Edward, she added: “He is 77 now and was unable to come so we feel it’s very nice Rosie is here at the same age.”
Another youngster in the crowd was Chloe Harkness, 11, who had never been to London before and had arrived feeling “in awe” of the place at 5.30am.
Chloe, from West Yorkshire, said: “I don’t know what I’ll say or do when I see the Queen’s coffin, I am a little bit nervous thinking about it, but I think it will give me goosebumps.”
Her queue neighbour Sara Brown, from Essex, told how as a 10-year-old girl in 1981, she was selected to give flowers to the Queen, who was boarding the Royal Yacht Britannia at Parkeston Quay, Harwich.
Sara, 51, said: “I was so nervous that I forgot to hand them to her. She smiled and said to me, “Oh! Are those for me?””
Former X Factor judge Sharon Osbourne, 69, handed out food and drink to those in the queue, describing them as “amazing people”. Those at the very front of the line had been camping out for days.