Train bosses insist a fire on board a train moments after it left Kettering on Thursday night (July 15) was an isolated incident.
But it followed another incident on an East Midlands Railway Intercity diesel-powered service just a week earlier.
Last night's service from London to Nottingham was halted at Leicester at around 8pm, 25 minutes after leaving Kettering.
Firefighters were scrambled to the platform and passengers evacuated from the station.
A spokesman for the train operator said: "Last night one of our class 222 trains suffered a fault which led to a small fire on the underside of the unit.
"Passengers were quickly and safely evacuated. No one was injured and the emergency services quickly dealt with the incident.
"The fault which caused the fire has been identified and work is taking place to repair the unit at one of our depots.”
Firefighters also dealt with a small fire under another class 222 train at Loughborough station on July 8 although East Midlands Railway did not respond to requests for a comment on that incident.
East Midlands Railway runs 23 Meridian units on its Intercity service between London and the Midlands, calling at Kettering.
Diesels were also used on services at Wellingborough and Corby until May when they were replaced by class 360 units as part of the the £1.5billion electrification of the Midland Main Line through Northamptonshire.
New Hitachi-built bi-mode 'Aurora' units, which can run on electrified and non-electrified tracks, are due to arrive during 2023 to replace the Meridians.