Thameslink was forced to close three platforms at about 7pm while the power was switched off and the herring gull was removed.

Services that were affected included Brighton to London and the Gatwick Express, with disruptions lasting until about 8.20pm.

The rail operator posted on X advising passengers to leave 20 minutes early to complete their journeys and check departure information regularly.

Several people replied to Thameslink asking if the news was a late April Fool joke, and questioning whether herring gulls are actually endangered.

One traveller complained that "numerous trains" had been cancelled and operators had left them "stranded in the rain".

Thameslink later said apologised for the inconvenience the incident caused to passengers, adding that the bird was safely removed from the railway.

"We're glad this had a happy ending," it said, sharing a photo of the young gull.

Despite the herring gull being a common sight in seaside resorts, the species has been on the Birds of Conservation Concern's (BCC) red list since 2009, because of ongoing population decline.

The red status means the species has been identified by the BCC as subject to "an increasing level of conservation concern".

The list is compiled by the UK's leading bird conservation organisations, including the RSPB, and identifies conservation priorities for birds.