Lady Eliza Manners, 24, told a magistrates' court a hefty penalty would cause "cash flow issues."

       The maximum fine is ￡100 although there is discretion to impose a lesser penalty.

       The interior designer, who lives in a ￡700,000 flat in trendy Notting Hill, west London, is the youngest daughter of David Manner, 11th Duke of Rutland.

       The family seat is Belvoir Castle, Leics, a location for movie The DaVinci Code and TV show The Crown.

       Lady Eliza was pictured on Instagram posing in designer clothes during a trip to Milan a few weeks before a speed camera snapped her behind the wheel of an Audi.

       She was driving at 47mph in a 40mph zone in Brentford, west London, last March.

       She admitted the offence online and was fined at Lavender Hill Magistrates' Court, south London.

       Asked if paying the penalty would cause difficulties, she wrote: "It would cause me cash flow issues."

       Her guilty plea was dealt with under the Single Justice Procedure on October 4.

       There was no hearing in open court and details emerged yesterday. On top of the ￡50 fine, Lady Eliza was ordered to pay ￡85 court costs and given three penalty points.

       What is happening where you live? Find out by adding your postcode or visit InYourArea

       With elder siblings Lady Violet and Lady Alice, the sisters were dubbed the "bad Manners girls" when regulars on London's social scene.