He began rock climbing just after World War II and became a founding member of a loose association of young climbers from the area who came to be known as "the Bradford Lads".
[1] Active throughout the United Kingdom, particularly the gritstone edges of Yorkshire and Derbyshire, the fells of the English Lake District, and the mountains of North Wales.
Another regular partner throughout his active career was his brother, Neville Drasdo, who became a formidable climber during this period in his own right and whose activities included an ascent with Joe Brown of one of the hardest British routes of its day, "Hardd" (now graded E2 5c) on Carreg Hyll Drem in Snowdonia.
Harold and Neville Drasdo were the first climbers to explore Poisoned Glen in Donegal, Ireland, and during an intensive period established several hard first ascents.
As a guidebook writer, Harold Drasdo wrote the first Fell & Rock Climbing Club guide to the Eastern crags of the Lake District in 1957.