As part of the campaign for the book, the publisher arranged for a specially branded Brougham carriage to take Horowitz to his book launch at Waterstones Piccadilly, stopping off at other Waterstones and the Sherlock Holmes pub on the way.
The author also visited some of the locations found in Moriarty, about two detectives – not Holmes and Watson – investigating the rise of a new criminal mastermind determined to fill the space left by the death of Moriarty at the Reichenbach Falls.
Orion used the hashtag #ISawMoriarty on Twitter, posting pictures of the tour and encouraging people who saw Horowitz and the carriage to tweet as well.
Waterstones stores on the tour were London Wall, Leadenhall, Trafalgar Square, Garrick Street, Oxford Street Plaza, Oxford Street, and Piccadilly.
The publicity campaign for Moriarty began earlier this year with a title reveal at London Book Fair, followed by an exclusive proof giveaway. Orion worked with the Museum of London on the opening talk in its events programme for its new Sherlock Holmes exhibition, which opened this month, and has arranged a number of media interviews and events.