Pippa Middleton was out and about without a ring on her engagement finger - despite reports she is set to wed her financier boyfriend James Matthews.
Hedge fund boss Mr Matthews got down on bended knee during a trip to the Lake District on Saturday to propose to the Duchess of Cambridge's sister, the Daily Mail said.
The couple have been dating for less than a year.
There was no sign of a ring on 32-year-old Pippa's left hand as she stepped out on Monday night at the Frost Summer Party Fundraiser.
The event, raising money for the British Heart Foundation's Miles Frost Fund, was held at Burton Court in London.
The couple had been seen at Wimbledon last week enjoying the tennis.
Pippa leapt into the public consciousness in 2011 when she was bridesmaid to her sister in a figure-hugging Alexander McQueen dress at the royal wedding.
Mr Matthews is the elder brother of former Made In Chelsea star Spencer Matthews, who reportedly left the show earlier this year after five series.
The reality television star was also forced to quit I'm A Celebrity ... Get Me Out Of Here! last year because he was taking "steroid-based medication" to bulk up for a charity boxing match.
Spencer later told the BBC he took the pills "completely out of vanity" because he wanted to "look good in the shower", but denied being addicted to them.