A promised train service into London that was supposed to open more than a year ago has been pushed back again.
The service's opening was pushed back to December this year, but there's been another delay.
In a joint letter Network Rail and GTR said: "We are united in our belief that we can never subject passengers to the same level of disruption ever again, and this has had a considerable effect on all subsequent timetable changes.
"Despite all our efforts, this means that we have had to take the regrettable decision that the Maidstone East Thameslink services cannot start operation in December 2019 as previously advised without seriously compromising reliability."
Earlier this week the Department for Transport refused to confirm if GTR would meet the December deadline.
He said: "Though it is extremely disappointing that Thameslink services on the Maidstone East line won’t be delivered in December as promised, this doesn’t come as a surprise. The government have made it clear for a number of months now that GTR were not in a position to deliver the service
"I have not been reassured during my numerous conversations with GTR over the past few weeks, and this is why I have made it clear through my updates what I expect to happen.
“I am focused on working constructively with GTR, and the Government, to make sure any improvements are delivered next year. This will at the very least help long suffering commuters using the Maidstone East line during the key times of the day when people are travelling.
“There is no doubt that this is bad news, but I will continue to engage with GTR to ensure that they eventually do deliver what was promised.”
The joint letter said Thameslink was undergoing more rigorous scrutiny than previous schemes because of disruption caused by the May 2018 timetable change.
It added: "Adding these services onto an already busy and complex railway network presents a real risk of delay and disruption to the thousands of passengers that rely on our existing train services, and we hope you can understand why we cannot allow this to happen.
"The entire rail network in the South East is integrated, which means that every change we make can have multiple knock-on effects to other services, all of which need to be worked through and mitigated."
GTR said it would try to open Thameslink "as soon as possible", but could not offer a provisional date.
Helen Grant, MP for Maidstone and the Weald said: "This is clearly very disappointing news. The Thameslink service from Maidstone East is long promised and much needed. It is totally unacceptable the people of Maidstone have again been let down in this way. Rest assured I am in constant communication with both Thameslink and the Department for Transport and I will provide a further update in the coming days."