Officers have been pursuing several lines of enquiry, including analysing CCTV footage from on the train and at several stations.
This was a very distressing incident for the young boy who was travelling on his own. Everyone has the right to use the rail network without the fear of crime and we are doing everything we can to catch the person responsible. I urgently want to speak to the man pictured as I think he could greatly help the investigation. If you recognise him, or have any other information, please get in touch.
Anyone with information is asked to contact British Transport Police** on 0800 40 50 40, or text 61016, quoting background B3 of 28/04/2014. Information can also be passed to the independent charity Crimestoppers on 0800 555 111.
More top news
Anthony Bristowe who is registered blind is cycling in tandem from Land’s End to Bradford-on-Avon.
Analysis of queues found drivers faced 1.35 million traffic jams, costing them in wasted time, fuel and unnecessary carbon emissions.
Wednesday's forecast for the west of the region from Holly.