Piccadilly:
Some people, *cough* Lavender Brown and Parvati Patil *cough*, believed that Hermione's Patronus memory was the day she first met Ron, or when he and Harry had saved her from that troll. Her closer friends, like Harry Potter himself, thought it might have been the time she received her Hogwarts letter, or when she was first called "The Brightest Witch of her Age". Only Draco Malfoy, lord of the ferrets ever got close to the truth, taunting one time that it was probably some "stupid thing with her filthy Muggle parents."
It was in fact, a day when she was about 7 or so; her "powers" just beginning to show. Her parents had been very busy that season and hadn't had time for little Hermione, but she had been promised a special outing as a surprise. So that Saturday morning, they had closed the dental practice for the day and drove all the way to Piccadilly Circus, where Hermione was allowed to buy a book and ice-cream and enjoy them while sitting across from the famous statue. It wasn't the outing itself that made her memory, but a seemingly unfortunate (or fortunate, she guessed) incident that followed.
Licking her toffee-flavoured treat contently, little Hermione failed to see an incoming body, who had accidently knocked into her and caused her ice-cream to fall onto the ground below. In a flash of petty rage, Hermione unknowingly caused a large raincloud to appear on top of the oblivious perpetrator, dousing them in water. Shocked, the boy had ceased walking beside his mother and turned around. He had white-blonde hair and strange emerald clothes. His almost silver orbs blinked as he took in the messy-haired brunette who stood with her hands balled up at the sides, happy with her revenge but shocked at the means.
"Don't worry, it happens to me too sometimes," he announced to three shocked parents. Putting his hand on her shoulder seriously (well as serious as a 7 year-old can be), he continued. "You'll grow into your magic." And with that, the boy smiled, bowed and followed his mother back into the crowd. Hermione Granger never forgot that day; the day she met a young boy who opened up a whole new world for her. The day she found someone who proved that she wasn't alone; there were others like her too.
When Draco Malfoy finally learned how to perform the charm other had praised Potter for knowing at 13, many thought that his "happy" memory was when he was put into Slytherin, or initiated into the Death Eater. Only Hermione Granger hit even close to the truth, one retorting it was probably something to so with harassing some poor Muggle while his Death Eater parents watched. His memory was that of one Saturday morning, when his mother had decided to grace him with her presence and a day out. It was a morning spent at Piccadilly Circus, when he had knocked a toffee-flavoured ice-cream out of a small bushy-haired girl's hand. It was the first time he realised that a girl in Muggle clothes could do the same thing as he could do: magic.