Network Rail undertakes much of its maintenance of the national rail network overnight and at weekends. At these times, parts of the network may be closed or only open to services travelling at reduced speeds, depending on the nature of maintenance work taking place.
If a service has to travel via a different route or at a reduced speed, this will affect the time which a train takes to complete its journey.
Detail relating to the specific services in question can be obtained from East Coast or Network Rail as follows:
Elaine Holt, Chair, East Coast, 1/18 Great Minster House, 76 Marsham Street, London SW1P 4DR; and
Iain Coucher, Network Rail, Kings Place, 90 York Way, London, N1 9AG.