The headquarters was also home to a grand staircase which led to a double storey library lit by skylights. During World War II, a bomb fell through the skylights which luckily only caused minimal damage to the building. By the 1920s the building was becoming too small for the needs of the college. It was eventually sold to the Canadian High Commission in the 1960s.
One of the most fashionable British architects of the early 1800s, John Nash, had remodelled parts of London’s west end at the time the Pall Mall site was built. He had submitted plans, which were rejected. Ironically, he also designed the building which occupied the site of the college's next headquarters in Regents Park. That building was demolished to make way for the fifth headquarters, having been badly bomb damaged during World War II.