Under the Sexual Offences Act of 2003, clauses designed to protect vulnerable people from abuse make it an offence to engage in ‘sexual activity with a person with a mental disorder impeding choice.’ Conviction can bring a maximum sentence of 14 years in jail.

The wife was told that if she continued to have sex with her husband, social workers would take ‘safeguarding measures’ to remove either her husband or herself from the home they shared with his parents.

Sir Mark said the wife moved into a separate bedrom, a snub her husband could not understand. The judge said: ‘In order not to lead him on she significantly reduced any physical expressions of affection. The impact of all this on the husband is not difficult to imagine.’