Fleeing robber who caused commuter delays after dramatic train line escape had first held up a Northampton jewellers

More detail has emerged from yesterday's rush-hour foot pursuit in which a man, believed to be in his early 30s, escaped a police dog unit and evaded the detection of the force helicopter.

The man was seen darting across the platform at Northampton Railway Station at 6.40pm before jumping on to the lines and fleeing into the darkness.

A police spokeswoman has now confirmed the man had first held up the Michael Jones jewellers in the Grosvenor Centre.

The spokeswoman said the robber had taken "high-value" jewellery from the store at around 5.30pm and escaped.

"He was chased through Spring Boroughs, before heading towards St Andrews Road," she added.

He then ran into the station, before breathlessly making his way across a footbridge and onto the lines itself as hundreds of commuters watched on.

The spokeswoman said the police dog unit then lost the man's scent, however a tweet from the proactive team at Northamptonshire Police said the man made his escape after assaulting a police dog.

The robber was described as a black man, who was wearing a black jumper and grey trousers.

CCTV images are likely to be released by police in due course.

Staff at Michael Jones declined to comment following the incident.