The damaging impact of new train timetables has been demonstrated in the latest punctuality figures.
Almost a quarter (23%) of trains operated by Northern were at least five minutes late between May 27 and June 23, compared with just 9% during the same period last year, Network Rail data shows.
This rises to 34% when only the firm's Lancashire and Cumbria routes are taken into account.
Some 6% of Northern trains were either cancelled or delayed by at least 30 minutes, up from 2% in the corresponding period in 2017.
The introduction of new timetables on May 20 also led to major disruption on Thameslink and Great Northern services in south-east England.
Thameslink saw more than a third (36%) of trains fail to hit the punctuality target, compared with 18% in the same period last year, while Great Northern's figure rose from 16% last year to 30%.
Transport Secretary Chris Grayling was accused of "personally propping up" failing rail franchises by the Rail, Maritime and Transport union on Sunday amid reports that Govia Thameslink Railway (GTR) - which includes Thameslink and Great Northern - could be about to lose its contract.
GTR was said to be "drinking in the last chance saloon", according to an unnamed Government source quoted by the BBC.
A series of failures have been blamed for causing the chaos, including Network Rail's late approval of the new timetables and delayed electrification projects, poor planning by train operators and the decision by transport ministers to phase in the introduction of new GTR services.
A GTR spokesman said: "Services on Southern have been performing much better since the introduction of the new timetable. Meanwhile, on Thameslink and Great Northern we are working hard with the Department for Transport and Network Rail to bring in a new, interim timetable that will give certainty and improved services."