The Night at the End of the Tunnel was produced by MVM London and attracted 2,100 guests to a temporary structure behind the new station on 19 September.
A two-hour reception was followed by a sit-down dinner catered for by Moving Venue Caterers. Comedian Al Murray performed to guests before a firework display and the unveiling of the new Eurostar train.
Caterer The Recipe fed 300 crew during the event's seven-week build and breakdown. De Boer supplied the 4,800sqm temporary structure, Brand and Deliver was behind all of the production, such as staging, lighting and AV, and Phoenix Fireworks produced the display.
LCR head of media Ben Ruse said: "We managed to track down all 2,500 people who worked on this huge project. People travelled from all over the world as they are now working on engineering projects in places like Dubai. We included anyone who worked with LCR from a bricklayer to an engineer."
MVM London is also organising the royal opening on 6 November, which will be attended by the Prime Minister, and two additional launch events taking place on 7 and 8 November.
MVM London director Stephanie Vaughan said: "We are also organising test events at St Pancras. We had to source 6,000 people to enter the station over five days as customers to test out how clear the signage is."