Shear madness 
https://www.constructionnews.co.uk/projects/olympic-stadium-costs-continue-to-soar/10014352.article
and as for this..
'The cost of installing the seats, which have been installed to improve the view for football fans, is estimated to increase to £8m from £300,000'.
https://www.constructionnews.co.uk/projects/olympic-stadium-costs-continue-to-soar/10014352.article
and as for this..
'The cost of installing the seats, which have been installed to improve the view for football fans, is estimated to increase to £8m from £300,000'.