Other researchers believe that some individual(s) may have been behind its origins, being followed by imitators later on. Spring-heeled Jack was widely considered not to be a supernatural creature, but rather one or more persons with a macabre sense of humour. This idea matches the contents of the letter to the Lord Mayor, which accused a group of young aristocrats as the culprits, after an irresponsible wager. A popular rumour circulating as early as 1840 pointed to an Irish nobleman, the Marquess of Waterford, as the main suspect. Haining suggested this may have been due to him having previously had bad experiences with women and police officers.