A 25-mile stretch of a major rail route will be blocked this weekend as contractors carry out improvement work.

Railtrack said the disruption on the west coast main line would add an extra hour to most journey times.

The upgrade will affect services for 18 consecutive weekends while lines between Milton Keynes and Hemel Hempstead are upgraded.

The route links London with the Midlands, North West and Scotland but has been hampered in recent years by an ageing infrastructure.

Virgin Trains and Silverlink Trains - who run services along the route - have arranged for 150 coaches to meet every train, transferring passengers from station to station.

Some will be express services while others will stop at all stations in between.

But disabled passengers will have to contact train operators in advance to arrange for specially-adapted transport.

The work is being carried out by Railtrack - which is in the process of being turned into a non-profit organisation, Network Rail.

Track and overhead lines will be replaced while a new junction will also be installed at Ledburn, in Buckinghamshire, to enable trains to go faster

Work to upgrade the line between Wolverhampton and Stafford will also continue throughout the summer.

Improvement work on the line has already been carried out at Euston, Willesden, Birmingham, Stafford, Ditton and in some areas of Manchester.