A charity event at the home of Pink Floyd drummer Nick Mason ended in "chaos", with people stuck in traffic for hours as they tried to leave.
More than 15,000 people went to Middlewick House near Corsham on Saturday and Sunday to view its extensive gardens and Mason's collection of supercars and classic vehicles.
But some drivers said it took people hours to leave the event, which raised money for Wiltshire and Bath Air Ambulance Charity and The Wiltshire Bobby Van Trust.
Organisers have since apologised for the travel issues but described the event as a success.
Donna Fielder attended the fundraiser and described it as "chaos".
"We were heading back to our car at about one o'clock and, as we walked through the top field, we could see rows of stationary traffic," she told the BBC.
"I barely moved 50m [164ft] in the space of an hour."
Ms Fielder said there was a "huddle" of marshals by the exit gate but claimed they "didn't have a clue".
"There were still cars being brought in – classic cars for viewing – and I think that's what caused a lot of it," she added.
"You had people jamming into lanes to create lanes to get out and then you've got six or seven cars diverging from different directions."
Organisers put new traffic measures in place for this year's event after similar issues in previous years. This included a separate entrance for cars arriving from Chippenham and diversions for non-event traffic.
A spokesperson for the Wiltshire Bobby Van Trust said: "This year's Middlewick House Open Garden event drew a record crowd of more than 15,000 people across the weekend, including an unprecedented number of people turning up on the Sunday to buy tickets on the door.
"We had people visit from across the UK – we apologise to those affected by the traffic build up around Corsham and those impacted by the delay exiting the car parks.
"We will be collating all feedback and adding it into our review process ahead of the 2026 event."
The trust works with Wiltshire Police to help elderly and vulnerable people with home security.
'Two hours to exit'
BBC Wiltshire's Jeremy Stern went to the fundraiser and said there were "hundreds" of cars trying to use one "narrow" exit.
"By the time the traffic started moving it was chaos, as frustrated drivers looked for any which way to get out of the car park," he said.
"The car park attendants did their best but there weren't enough of them to marshal so many lines of traffic.
"It took two hours for us to get out. Some people I spoke to said they had been waiting even longer."
