The two-tier propped cantilever Portman Stand was built along the east side of the ground in place of the existing terraces in 1971, providing 3,500 additional seats and increasing the capacity of the ground to approximately 37,000. Advertising appeared around the perimeter of the ground in the same year, while the following year saw the construction of the "Centre Spot" restaurant underneath the Portman Stand. Additional seating was added to the Portman Stand in 1974 and the ground saw its record attendance of 38,010 the following year in an FA Cup tie against Leeds United. Following success in the 1978 FA Cup, the club invested in 24 executive boxes in front of the Portman Stand and, as a result of the Safety of Sports Ground Act (1975), reduced the capacity in front by introducing seats, taking the overall capacity down to 34,600.