It was revealed last night that Wembley's retractable roof will take 40 minutes longer to close than originally planned, despite initial plans stating that the roof for the new stadium would take just 15 minutes to close.
The engineering magazine New Civil Engineer has discovered the process will now take 56 minutes and 30 seconds - and recommends that the roof is shut only when the stadium is empty.
But Wembley National Stadium Limited said the FA Cup final would not be affected. A spokesman said: "This won't be a problem on final day because we will decide in the morning whether the roof will be open."
A statement from the builders Multiplex last night read: "The roof has a capacity to close within one hour. It has been tested many times."