The western range package of works is the biggest of the redevelopment and will bring about tremendous improvements to one of London's busiest stations.

The new semi-circular structure to the west of the station will house a spacious 8,000sq metre concourse - three times the size of the existing one and include the installation of voltaic roof panels which enable the building to be self heating and much brighter than the current station.

Ian Fry, King's Cross project director said: "This represents a key turning point for the project, and I'm delighted that work can really get moving on what is visually the most exciting aspect of the redevelopment.

"The new western concourse will deliver fantastic improvements for passengers using King's Cross, with more space, easier connections to regional services and a lighter, brighter environment to improve the whole travelling experience."

Tim Peach, managing director, Taylor Woodrow said: "This is a strategic success for us as a business. We are delighted to be back at King's Cross following the successful completion of the Western Ticket Hall. Rail is a key market for the skills, behaviours and experience of our team, and our supply chain partners, gained from current and previous rail projects."

Network Rail is investing over £400m in redeveloping King's Cross station.  Once completed, 50m passengers will use the new station each year - 10million more than today. An additional platform, increasing reliability and capacity at the station will be built. 

The majority of the station redevelopment will be completed by 2012 in time for the Olympics with the transformation complete by 2013.