Police want to identify a number of rail enthusiasts pictured trespassing on the tracks to catch a glimpse of Flying Scotsman following a decade-long refit.
Images taken from a helicopter operated by Network Rail (NR) show a number of people standing close to rail lines to watch the famous locomotive travelling between Newcastle and York.
Anyone who recognises the people in the photographs is asked to contact British Transport Police (BTP) so it can "enforce the law where appropriate".
The photographs, taken on May 14, show that repeated warnings about the dangers of getting too close to the railway are being ignored by some people.
Flying Scotsman's inaugural run on February 2 was marred by trespassers who walked along the tracks taking photographs as other trains passed on opposing lines.
All trains on the East Coast Main Line were temporarily stopped and taxpayer-funded NR was forced to pay out almost £60,000 in compensation.
Some 59 train services were delayed for a combined total of more than eight hours.
Chief inspector David Oram of BTP said people have put themselves at risk during Flying Scotsman's tour of England and Scotland despite "advice and numerous warnings".
He went on: "In order to keep the public safe we will enforce the law where appropriate, which is why we are releasing the images of people trespassing today in a bid to trace those responsible.
"If you recognise yourself or any of the people pictured in the images please contact us.
"We will continue to identify and take action against trespassers on future journeys to ensure that these pass safely and free from disruption."
Rob McIntosh, route managing director for NR, said: "While I must thank the vast majority of people who have been out to see Flying Scotsman for staying safe, it is deeply worrying to see people standing trackside.
"Tens of thousands of people have been out to see this railway icon on its tour of the country so far, but even one person trespassing is one too many.
"The threat of serious injury is real, as well as causing delays to passengers travelling on other services, and we will continue to work very closely with the British Transport Police to keep our railway safe and to make sure spectators remember their day out for all the right reasons."
Anyone who recognises the people pictured is asked to contact BTP by calling 0800 40 50 40 or texting 61016, quoting reference 314 of 2/6.