Sheffield Wednesday F.C.
Expert believes safe capacity of the stadium was about 30% lower than the number of tickets sold.
Graham Mackrell was secretary and safety officer for the club at the time of the Hillsborough disaster, court hears.
The trial of match commander David Duckenfield is ongoing.
The former Sheffield Wednesday officer is accused of health and safety offences relating to the 1989 disaster.
The charges relate to the tragedy at the Hillsborough stadium 1989, in which 95 people died.