St Fagans National Museum of History in Cardiff topped the list with a customer score of 94% in the survey of almost 7,000 people.

The National Railway Museum in York and Durham Cathedral were also among the UK's best free days - the former tied with the Royal Air Force (RAF) Museum in Cosford with a score of 91%.

Other free museum and galleries which made the list included the National Museum of Scotland (90%), the Cardiff National Museum (87%), Kelvingrove Art Gallery and Museum in Glasgow (87%), Royal Air Force Museum, London (87%) and Walker Art Gallery in Liverpool (87%).

Which? also asked almost 3,000 people for their favourite historic attractions, ranking them using nine criteria, including food and drink availability and lack of crowds.

Durham Cathedral finished top of that ranking with a score of 86%. St David's Cathedral (80%) and Chichester (77%) also rated highly.

They were followed by the Houses of Parliament on 76% as any UK resident can request a free guided tour by contacting their MP, or a member of the House of Lords.

'Cheap days out never more important'

Which? Travel editor Rory Boland said the UK had "a number of fantastic museums, galleries and other attractions".

"As the cost of living crisis continues to be a strain on household budgets, finding cheap or free days out has never been more important," he said.

"Fortunately, the UK has a number of fantastic museums, galleries and other attractions which offer free entry and hours of fun."

Read more from Sky News:
Missing dog found in ambulance after eight-month search
Reynolds and McElhenney donate to children's ward

Janice Lane, director of visitor experience for Amgueddfa Cymru - Museum Wales said she was "delighted" St Fagans had secured the top spot.

"We are delighted that St Fagans National Museum of History is the top-rated free attraction in the UK once again and want to say thank you very much to all those who voted to help get this award," she said.

"This award is testament to the quality and warmth of the welcome we offer to all our diverse audiences."