Pre-tax profit fell £7 million (13.7%) from the £50 million posted during the six months to June 30, 2017.

Operating profit, meanwhile, slipped 14.3% to £63 million during the same period.

This was despite visitor numbers topping 30 million, up from 29.7 million during H1 last year.

Merlin said the results cover “seasonally quiet period”, with 70% of EBITDA typically generated during H2.

Adverse movements in foreign exchange and a weak dollar were the main factors affecting profit, said Merlin.

The operator added its decline in operator profit was partly the result of depreciation on new business developments such as the transition of LEGOLAND Japan into a fully fledged resort with accommodation, and the expansion of existing accommodation at LEGOLAND results in California and Germany.

Nick Varney, Merlin chief executive, said the group had been pleased by customer reaction to its investments, and was continuing to see recovery at Alton Towers.

He added the “recent warm weather” in Northern Europe had “undoubtedly” benefitted the business.

Having so far traded in line with expectations, we are now entering our peak season where we generate the majority of our annual profit,” said Varney.

“With many exciting new initiatives and launches to come in the future, we remain confident in our long term prospects."

Merlin said it was also delivering on its strategy, including transforming its theme parks into destination resorts with 644 rooms planned to open in 2018 across its LEGOLAND theme parks in Japan, California and Germany.