A couple who engaged in ‘sexual activity’ on a train sparking complaints by other passengers are being sought by British Transport Police.

Police are investigating reports of indecent behaviour by the pair on the 11.14pm King’s Cross to King’s Lynn train on Wednesday May 11.

They are appealing for witnesses PC Tony Orton said: “We were contacted by passengers on the train who were offended by what they saw.

“It is completely inappropriate to engage in sexual activity on public transport and we need to speak to the couple about their behaviour.

“I need to hear from anyone who saw them, particularly if you know where they left the train or who they are.

“They travelled beyond Cambridge towards King’s Lynn, but it is unclear where they left the service.”

Anyone with information is asked to contact British Transport Police on 0800 40 50 40, or text 61016, quoting reference 163 of 19/05/2016. Information can also be passed anonymously to Crimestoppers on 0800 555 111.