The corporation is looking for a firm to first build a prototype to test the engineering before going ahead with plans to build and maintain the movable lower seating tier.

A key challenge will be to design the retractable system while protecting the athletics ‘mondo’ track and maintain the total stadium seating capacity of 54,000 spectators for pitch sports and up to 58,100 for athletic events.

The stadium will function as an athletics arena with seating withdrawn and a football ground with the four sides of the lower bowl pushed towards the pitch by automated motors.

The initial designs provide for seating distances that would compare favourably with the Emirates and Wembley and the top stadia around the world.

West Ham Utd favours a design that brings seating 10m closer to the goal line than the Stade De France in Paris, which boasts a similar system.

Conversion plans will also involve a seating bridge between the upper and lower tiers on the East side to create a large “Kop” style stand.

Firms have until 1 November to submit prequal applications. Further details are available from the supply4london website.

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Seating in football mode

Athletics stadium mode