The Hogwarts Express is the name of the train that makes a run between London, Kings Cross Station Platform 9¾ and Hogsmeade Station. It makes this run at about six times a year, maybe more, as needed.
The Express dutifully carries students to and from Hogwarts School of Witchcraft and Wizardry at the start and end of every term. The train leaves Platform 9¾ without Fail on 1 September at 11 o'clock in the morning, arriving at Hogsmeade Station in the early evening. Some Students take the train back to Kings Cross Station to go home for the Christmas and Easter Holidays, but some do not. as they stay at Hogwarts. It also makes the run back again to London at the end of term in June.
When looking for this cache make sure you please put it back where and how you found it, and be careful there could be muggles lurking around!
No need to go on inside of fence.