For any Harry Potter fans, on 1 September each year, there is a meeting of fans at Kings Cross station.
On that day the 1100 train to Hogsmead is on the departures board, and is also audibly announced.
But please note that there is no physical special train either at platform 9 3/4 or any other platform.
Also the nearby Everyman Cinema will screen all 8 movies back to back starting at 1230.