The head of rail experts which advised Govia Thameslink Railway on its major timetable change has said he is "absolutely mortified" by recent disruption.
Chris Gibb, chairman of the Thameslink 2018 Industry Readiness Board (IRB), explained to MPs how "extremely sorry" he was to passengers.
Thousands of delays and cancellations have hit fed up commuters since the introduction of the new timetable on May 20.
Mr Gibb said: "Between May 4 and May 20 that's when the time really ran out and it was just impossible to get enough drivers in the right places with the right skills working to the very inefficient plan that had been prepared at the very last moment when the timetable was eventually agreed.
"If we'd had more time on any level we would have made a better job of it."
"I'm absolutely mortified that things have gone wrong."
The IRB was a team of 20 people including representatives of the train operators, Network Rail, regulator the Office of Rail and Road and the Department of Transport.
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