From 21 July until 4 August 2006 , a example of the train was on show at Euston Square Gardens , near Euston Square tube station , for a Customer Acceptance Test followed by public display . From 21 July to 4 August 2006 , a mock-up of the train was on show at Euston Square Gardens , near Euston Square tube station , for a Customer Acceptance Test followed by public display .