Flexible flight tickets can be £1,700 more expensive than standard fares says Which?

In a Which? study the biggest percentage increase in price between a standard and flexible fare was for a British Airways flight from London Heathrow to Barcelona in February 2021 - 1,594%. https://www.dailymail.co.uk/travel/travel_news/article-9052393/Flexible-flight-tickets-1-700-expensive-standard-fares-says-Which.html?ns_mchannel=rss&ns_campaign=1490&ito=1490