Police are trying to trace two teenagers they believe are connected to an attempted robbery and assault on a Thameslink train from West Hampstead.

The duo boarded a service at West Hampstead station at 8.20pm on Thursday April 5.

The boys were being anti-social and were threatening passengers.

A man intervened, and challenged the boys’ behaviour, asking them to stop.

However according to the British Transport Police, they became instantly aggressive and started to assault the man.

When he left the train at Harpenden, the youths assaulted him further and tried to steal his rucksack.

Luckily, despite the attack, the man didn’t sustain any serious injuries.

Officers believe the teenagers shown in the CCTV images may have information which could held the investigation.

Anybody with information can contact the BTP by texting 61016, or by calling 0800 40 50 40, quoting reference 656 of April 5.

Or those wanting to give information anonymously can call Crimestoppers on 0800 555 111.