The whole launch campaign for Maigret was co-ordinated by Simenon and remains a significant event in the history of the publishing. There were innovations in every area: for the first time, a photograph was used for the cover of a book and for the first time, radio was used to launch a novel but it was the fancy dress ball that pulled off the success…

Simenon decided to "launch Maigret" in style, with a massive bal anthropométrique (named after the police department where suspects were stripped naked, measured and photographed). Designed by poster designer Paul Colin and the artist Don, it was held in a nightclub called La Boule Blanche, in the Rue Vavin, Montparnasse – then the fashionable pleasure capital of the city on 20 February 1931.

The invitations for this event were designed like a police record card and sent to everyone who was anyone: the smart set of Paris. The card seemed to come from the Criminal Records Office of Judicial Identity and in one corner there was a fingerprint. All the guests had to come dressed as policemen or criminals and were fingerprinted at the door.

It was a noteworthy evening. They had sent out a thousand invitations and four thousand people invaded La Boule Blanche. There was a contest for the most beautiful anthropometric head: the painter Kisling won first prize in the men's category, Suzy Solidor for the women. By two o'clock in the morning, Fayard's entire marketing budget of 20,000 francs had been swallowed up, Simenon had to assure the owner of La Boule Blanche that he himself would guarantee the remaining costs. At four o'clock, the cellars of the cabaret were empty. They had to cross the boulevards Raspail and Montparnasse to search for whisky and champagne at La Coupole.

The following day Simenon and his Commissioner Maigret were famous. They were in every newspaper.