Tunnelling work to link the HS2 high-speed train route to Euston has begun, in a major milestone for the troubled project.The first of two 1,624-tonne tunnel boring machines was set in motion on Tuesday afternoon, watched by Rail Minister Lord Hendy and Darren Jones, the Chief Secretary to the Treasury.The machine is named “Madeleine” after the former president of the Women’s Engineering Society, Madeleine Nobbs.