The train driver's union ASLEF notified train operators of its ban on overtime work, meaning Thameslink services will not make it to the south coast.

Instead, its Brighton trains are to terminate at Three Bridges in the town of Crawley, some 23 miles (37km) from where the Pride festival is taking place.

The strikes come as Storm Antoni hits the seaside town with strong winds and heavy rains for most of the day, as a Met Office yellow weather warning remains in place for the area.

Thameslink, part of the largest UK railway franchise GTR, announced the news with a "heavy heart", urging those going to Pride to seek alternative means to get there and acknowledging how "extremely difficult" it would be.

The train operator added its "ultimate aim [was] to keep people safe on this occasion" in a statement.

'Truly devastating news'

Responding to the travel disruption, Pride managing director Paul Kemp made it clear he was opposed to GTR's decision for a complete Saturday shutdown.

Conveying disappointment, Mr Kemp said: "This will come as a huge shock for not only Pride and the LGBTQ+ community but all the businesses preparing to welcome guests to our city from across the UK and world.

"Many Pride visitors have already booked and paid for Saturday night accommodation locally, they will now have to change plans or find an alternative way to get into the city.

"It's truly devastating news for everyone."

He added it was "very sad" to see GTR implement a service shutdown rather than "finding a working alternative".

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Pride and the rail operator acknowledged they both had a long-standing relationship with each other as Thameslink said it usually runs a "significantly enhanced service" for the festival every year with extra late night trains.

Services will run to and from Brighton on Sunday as normal as Pride festivities continue.