The Percy family home is Alnwick Castle in Northumberland

The Duke of Northumberland's 21-year-old daughter Lady Catherine Percy, has now been warned about her driving by her aristocratic parents.

The warning from the Duke, one of Britain's wealthiest men, followed a week in which his daughter was due to appear in two different courts in the space of three days.

On 29 July, magistrates at Harrogate banned Lady Caroline for six months and fined her �300 for breaking the 70mph limit on the A1M at Boroughbridge, on 5 May this year.

On 31 July, the motor racing enthusiast was to have appeared before magistrates in Newcastle on a charge of exceeding a 30mph speed limit on the outskirts of the city in February this year.

A letter was submitted to that court asking for the case to be dealt with in her absence, but the bench refused and adjourned the case for Lady Catherine either to appear in person or enter a plea by letter.

Lady Catherine, who lives at Alnwick Castle, has now apologised to her parents and been warned about her behaviour.

The Duke has accepted his daughter's apology

A spokesman for the Duke of Northumberland, said: "Lady Catherine accepts the court ruling and apologises for her excessive speeding.

"Lady Catherine, who is mid-way through a three year car mechanic course, has a keen interest in motor racing.

"The Duke and Duchess have accepted their daughter's apology, reminding her that speed on the track should not be duplicated on public roads."

The Duke and Duchess, who have two sons and two daughters, own land, homes, art treasures and other assets worth an estimated �300m.

In 2002, more than 120,000 people visited their castle home, seat of the Percy family since 1309.

It has featured in recent Harry Potter films.

The Duke of Northumberland is currently at the centre of a wrangle over whether one of his paintings should be sold abroad or kept in the country.

The Heritage Lottery Fund has agreed to make an �11.5 million grant to help keep Raphael's Madonna of the Pinks in Britain.

The Getty Museum in California has offered Duke of Northumberland �35m for the picture.