Party princess Bea hits town with Eugenie while glum mum Fergie dines with boyfriend just down the road

Princess Beatrice and Princess Eugenie hit the town last night to attend the launch of Form, a luxury menswear brand designed by Petra Ecclestone - the 19-year-old daughter of F1 mogul Bernie Ecclestone.

And their mum Fergie was also out and about, dining at The Dorchester with her Norwegian tycoon boyfriend Geir Frantzen.

The princesses smiled for the cameras at the event at Harrods in Knightsbridge and seemed to be having a nicer time than their mum who looked rather glum as she made her way home.

Pair of princesses: Eugenie and Beatrice last night at Harrods in Knightsbridge

The clothes launch was attended by Bernie Ecclestone, who has financially backed his daughter's business, his wife Slavica, racing car enthusiast Jay Kay and tennis star Boris Becker.

The royal sisters, no strangers to money or power themselves, looked poised and elegant but were in danger of being outshone by Petra and her sister Tamara who one day stand to inherit their father's £2.4billion fortune.

Super sisters: ( l-r) Eugenie, Tamara and Petra Ecclestone and Beatrice

On form: Bernie Ecclestone with Petra and wife Slavica at the launch last night

As her daughters mingled in Knightsbridge, Sarah Ferguson was in nearby Park Lane eating at China Tang at The Dorchester with boyfriend Geir Frantzen.

After they had eaten, the couple stood in the restaurant's hallway having a chat for about half an hour as their chauffeur-driven car waited for them.

They then emerged separately looking a bit serious, with Fergie even biting her nails as they drove away.

Glum: Sarah Ferguson and Geir Frantzen looked a bit down in the dumps as they left The Dorchester last night