Network Rail has apologised to passengers following disruption to services when overhead wires were damaged during last week's heatwave.
The overhead lines near West Hampstead were damaged when temperatures soared on Thursday, which affected the services ran by East Midlands Trains.
Network Rail say engineers worked round the clock to fix the problem, with East Midlands Trains operating a full service since Monday.
Rob McIntosh, Managing Director, Eastern, for Network Rail, said: “We would like to apologise to all passengers who have been impacted by this issue.
“Network Rail engineers have worked round the clock to fix the damage and this work is now complete, meaning that all services on the Midland Main Line can now run as normal. We would like to thank passengers for their patience whilst this took place.”