Thompsons partner Richard Arthur said: "This is a great day for London and for British workers. But the Wembley Stadium experience where an attempt to impose new working conditions resulted in industrial action must be remembered when awarding contracts.

"London 2012 cannot be put off while projects delayed by disputes caused by management riding roughshod over workers' rights are ironed out. Protecting the rights of the workforce employed to create this great event will be key to ensuring London 2012 fulfils everyone's expectations."