Edward Fitzalan-Howard's lawyer reportedly argued he needed his licence to organise King Charles III's coronation.
England's most senior duke, who organised the Queen's funeral, has been banned from driving despite saying he needed his licence to arrange King Charles III's coronation.
Edward Fitzalan-Howard, a 65-year-old aristocrat, was caught using his mobile phone and running a red light while driving his BMW in south-west London in April.
He admitted the offence but tried to avoid the six-month driving ban by claiming "exceptional hardship" due to his responsibilities.
In his role as Duke of Norfolk, he helped to organise the funeral of Queen Elizabeth II in September, which around 28 million Britons watched on TV.
Fitzalan-Howard, the most senior member of England's peerage system, is also tasked with arranging King Charles III's coronation next year.
The BBC reported that lawyer Natasha Dardashti told a court in London: "He must be mobile to achieve what he needs to achieve in this regard.
"His Grace needs to be able to organise what is a huge event."
But magistrates imposed a six-month driving ban on the duke, who had two previous speeding offences on record, and ordered him to pay £1,200 (€1,347).
"We accept that this is a unique case because of the defendant's role in society and in particular in relation to the King's coronation," chairwoman of the court's bench, Judith Wray, said.
"The hardship needs to be exceptional and although we find inconvenience may be caused, we don't find it exceptional hardship."
Fitzalan-Howard, who was educated at Oxford University, inherited the post of the 18th Duke of Norfolk after his father died in 2002.
The title links to England's historical peerage system and means that the duke is responsible for organising state ceremonies.
He was one of a handful of people who signed the Accession Proclamation after the Queen's death, which marked the transition of power to King Charles III.