A broken down train has caused headaches for Thameslink and evening commuters alike after attempts to budge the faulty locomotive with a rescue train failed.
The train broke down on Thursday evening between Kentish Town and West Hampstead and has caused "major disruptions" to services between London St Pancras International and Luton, Thameslink said.
It said: "Attempts were made to move the faulty train using a rescue train however this was unsuccessful and the line is now expected to remain closed until at least 2200."
East Midland Trains services were being delayed by 30 minutes as a result and disruptions expected to continue until the end of the day.
But Thameslink advised customers could use their tickets on "reasonable" bus, overground and underground routes, with replacement buses ordered but not due to arrive until 10pm (GMT).
Customers affected by the fault tweeted their frustration at the delay and warned others to dodge the disruptions before it was too late.
One tweeted, sarcastically: "Train broken down at Kentish Town. Send rescue train to push it out the way. Rescue train not powerful enough. Well done everyone."
Another said: "Looks like I'll be spending my evening sitting on a broken down train somewhere between Kentish Town and West Hampstead."
Meanwhile, commuters faced delays of more than a hour on Thursday after trains were cancelled and disrupted across the entire South West network because of poor rail conditions as a result of "leaf fall".
Areas affected included Weybridge, Portsmouth, Southampton and Basingstoke.
A spokeswoman for South West Trains said: "We are sorry for the disruption customers have experienced this evening as a result of poor rail conditions across parts of our network."
?Mick Cash, general secretary of the Rail, Maritime and Transport union, said: "How much more of this unprecedented chaos on Govia Thameslink Railway have passengers got to endure before the Government pulls the plug on this basket case franchise?
"They are a sick joke and are getting worse by the day. Chris Grayling and the Tory Government should be hanging their heads in shame and instead of propping these racketeers up they should be slinging them off the tracks and taking the services back under public control."
Shortly before 9.30pm, Thameslink tweeted it had just been informed the broken down train would be "moved imminently".
It said both lines should be able to reopen after this was completed.
Meanwhile, the National Union of Rail, Maritime and Transport Workers (RMT) took aim at what general secretary Mick Cash deemed "unprecedented chaos" on the Govia Thameslink Railways.