A morning train to Gatwick Airport was cancelled after two squirrels boarded and one refused to leave, forcing passengers to relocate from the "frightened and erratic" animals to another carriage, the BBC reported.
The squirrels had hopped on the Great Western Railway (GWR) service from Reading to Gatwick on Saturday and may have become distressed in the confined space, a spokesperson for the train operator said.
According to GWR, passengers moved to a different part of the train after the squirrels entered the rear carriage, which the train manager then locked. A Network Rail employee attempted to remove the animals at Redhill, but the 08:54 BST service was ultimately terminated when one squirrel wouldn't leave.
Staff tried to shoo the furry free-riders off when the train reached Redhill, Surrey, but one squirrel refused to disembark, GWR said.
The squirrel that stayed behind was returned to Reading. A GWR spokesperson humorously commented, "We can confirm that the 08:54 Reading to Gatwick service was terminated at Redhill after a pair of squirrels boarded at Gomshall without tickets, violating railway bye-laws. We tried to remove them at Redhill, but one refused to disembark and was returned to Reading, bringing an end to this nutty tale."
There are an estimated 2.7 million grey squirrels in the UK and their population is growing, according to the Woodland Trust, a conservation charity.
In a similar incident last December, a hedgehog was found hiding under a train seat on a service between Weybridge and London Waterloo. The animal, later named Hector, was adopted by a rail worker and his family.