I N ANY OTHER week, for any other prime minister, it would have been a career-threatening scandal. On September 22nd the Sunday Times published a cracker of a story alleging that during his time as mayor of London in 2008-16, Boris Johnson failed to declare his friendship with Jennifer Arcuri, a young American businesswoman then resident in London. According to the paper, Ms Arcuri joined three foreign trade missions with Mr Johnson in one year, despite being ineligible for any of them. She also received at least £11,500 ($18,000) in funding from London and Partners, a promotional body overseen by the mayor. Another of Ms Arcuri’s companies received £100,000 from the culture department. Mr Johnson spoke at several tech gatherings organised by Ms Arcuri and is said to have frequently visited her Shoreditch flat during lunch breaks, for what she reportedly says were technology lessons.

But this is not any other week. Asked about his links to Ms Arcuri on his way to the UN general assembly, Mr Johnson six times refused to answer. When he eventually broke his silence, it was only to say: “Everything was done with complete propriety and in the normal way.” Reporters scented blood. Yet after the Supreme Court delivered its dramatic verdict on September 24th, the Arcuri affair was relegated to the middle pages.

Nor is this any other prime minister. In his two months in office Mr Johnson has made a habit of violating the norms on which the British system of government is based. Dan Hough of the Centre for the Study of Corruption at the University of Sussex likens the British system to cricket, where lots of rules are unwritten but respected nonetheless. Contrast that with football, where players feign fouls to gain control of the ball. Mr Johnson’s government is applying the logic of football to a system run more like cricket. Once such codes are breached, it can be nearly impossible to reinstate them, says Mr Hough. And the more often it happens, the less scandalous it appears.

The penalties can be light, too. The London Assembly has given Mr Johnson 14 days to provide a timeline of his contact with Ms Arcuri and to explain his relationship with her. But although it can investigate breaches of its code of conduct, it “has no legal powers to apply formal sanctions”. Parliament has an “independent adviser on ministerial interests” who is empowered to conduct investigations—but only if instructed to do so by the prime minister.