The owner of theme parks including Alton Towers and Legoland is to make it more costly to visit on a sunny bank holiday than a rainy day midweek.

Merlin Entertainments, which also runs the London Eye and Madame Tussauds, is introducing "dynamic pricing" so prices can respond faster to weather and demand.

Merlin said it would help offset a decline in visitors since the pandemic.

Around 20 of its global venues will see the changes this year.

Merlin Entertainments already uses off-peak and peak time pricing which, like many organisations, allows seasonal fluctuations to dictate demand and therefore price.

But the introduction of machine learning will make flexible ticket pricing faster and more detailed.

For example, if a sunny Saturday during the summer holiday turns out to be less busy than expected, the firm could lower ticket prices on the day.

Similarly, if a winter's day unexpectedly turns out to be busy, prices could rise higher than current off-peak prices, even during what is normally considered a cheaper time to visit.

Merlin said in a statement that such a pricing structure "makes sure that the peak period experience is optimised by avoiding overcrowding".

It added that "these changes enable greater flexibility for guests booking online to choose discounted prices for select dates and times".

"We had it in 2023 and we had the highest guest satisfaction scores in the history of the company, and seven million additional guests," chief executive Scott O'Neil said. "So we're definitely getting the signal that our processes are moving in the right direction".

However, there has been some criticism of the "dynamic pricing" model used by companies such as Uber and restaurants, partly due to its lack of transparency about why prices are high some of the time.

In February, US burger chain Wendy's was quick to clarify that it was not introducing dynamic, or "surge" pricing. One of the company's most high-profile critics, left-wing senator Elizabeth Warren, said the plans meant people "could pay more for your lunch, even if the cost to Wendy's stays exactly the same".

Meanwhile, Mr O'Neil said "dynamic" pricing would help "protect the guest experience" during busier times of the year by managing queues, where waits of more than an hour are routine.

Merlin said on Monday it had made record revenues of £2.1bn in 2023, an increase of 8% year on year, with much of the revenue coming from international tourists visiting the capital. Nearly one in every four visitors to London came to a Merlin attraction, the company said.