Ashley Cox has been sentenced to 16 weeks behind bars, suspended for 18 months having been found guilty at an earlier hearing.
The 35-year-old went trackside one afternoon last August, climbing the gantry where he remained for two hours, before being arrested.
His actions led to the delay and cancellation of train services up and down the line, disrupting thousands of passenger journeys.
BTP Sergeant Mike Overington said: “BTP’s specialist teams investigate trespass and interference with railway infrastructure, and we’ll always use the legislation at our disposal to push for prosecution for behaviour that puts the safety of passengers and staff at risk.
“The consequences of Cox’s actions were felt by thousands of people, and this outcome sends a clear message that such behaviour will not be tolerated.”
Paul Langley, Head of Security, Crime and Resilience at Network Rail, said: “Trespassing on the railway is incredibly dangerous. Trains in the south east are powered by the electric third rail, which carries 750 volts and is easily enough to kill or cause devastating life-changing injuries.
“We hope this sentence sends a message that trespassing on the railway will not be tolerated. Ashley Cox is lucky to be walking away with a suspended sentence as it could have ended in tragedy.
“Incidents like this are a stark reminder of how quickly things can go wrong, and why we always take trespass so seriously.”
Jenny Saunders, Customer Service Director for GTR which runs Southern, Thameslink and Gatwick Express services, added: “We work hard every day to keep people safe and trains running. Ashley Cox’s actions not only put his own life at risk, but caused huge disruption for thousands of passengers trying to get home, or to see friends and family.”
