Wanted: university graduates aged between 20 and 35 years, with no criminal record and a height of at least 170cm (5.57ft) for men and 158cm for women. Military veterans or police college students preferred.

The very public ads have been cropping up online, posted by recruiters across China in search of people for a very discreet role.

The applicant’s mission, if they choose to accept it, is to keep an eye on disgraced officials at detention centres operated by the Communist Party’s disciplinary wings.

A search of job sites and Chinese social media revealed that security agencies and disciplinary bodies in at least 15 provinces had such “caretaker” positions going at detention centres last year, with some provinces seeking to fill hundreds of vacancies.