The line is blocked in Hertfordshire, with Peterborough services affected.
Engineers were on site to fix a "complete failure of the signalling system".
The service went through a junction in Hitchin at more than twice the speed limit.
Buses will replace trains for late night and early services between King's Lynn and King's Cross.
Since 2011, Matthew Streeton's voice has been heard by millions of train passengers in London.
Digital signalling work is being carried out, meaning several services will be replaced with buses.
Govia Thameslink Railway says the maps will allow people to gain more confidence at some stations.
Thameslink and Great Northern said their services will be cancelled or revised on Saturday.
Govia Thameslink Railway wants to recruit people and teach them how to maintain its fleet of trains.
