Britons will spend £2.7bn this summer on more than 50m summer outfits that will be worn only once, a poll reveals.

By far the biggest extravagance is new clothing for holidays, where consumers splash out more than £700m on 11m items bought for the trip which will never be worn again, according to research carried out by Censuswide for the charity Barnardo’s.

Wedding guests spend an average of £79.76 on a new outfit – nearly 10m of which are expected to only be worn only once.

The children’s charity warns this is another example of the huge environmental and financial impact of fast or throwaway fashion, amid growing concerns that the industry is wasting valuable resources and contributing to the climate crisis. It is urging shoppers to consider second-hand clothing rather than only buying new outfits.

Javed Khan, Barnardo’s chief executive, said: “Choosing to buy ‘pre-loved’ clothes for a special occasion means you don’t have to worry about bumping into someone wearing the same outfit.

“It is also kinder to the environment and your wallet, getting more wear out of clothes which might otherwise only be worn once and end up in landfill.”

Despite troubles on the UK high street, the fashion sector has continued to grow and the globalised supply chain has triggered a proliferation of cheap clothing, with a quick turnover that encourages consumers to keep buying. The cut-price online retailer Missguided came under fire recently for launching a £1 bikini.

A quarter of those questioned for the poll said they would be embarrassed to wear an outfit to a special occasion such as a wedding more than once, rising to 37% of young people aged 16-24 but just 12% of those over 55.

More than half (51%) of those surveyed said buying new clothes for a festival or holiday added to the excitement of the build-up.

Following its year-long investigation into fast or throwaway fashion, the cross-party environmental audit committee recently called for a penny tax on every garment sold to fund recycling initiatives, plus a ban on incinerating unwanted clothes – demands rejected by the government.