On the east coast of Yorkshire, where I was born and bred, and especially in Flamborough, the 'Great Storm' always meant the one that ocurred in February 1871 when 30 ships and boats and 70 lives were lost. Grimbsby was especially hard hit and the Bridlington lifeboat saved 16 lives before being overwhelmed. I've always thought of Three Score and Ten, which I've been singing since I first heard the Watersons perform it in the mid 1960s, referred to this storm but somehow the month was wrong. There were other big storms, in 1894 and 1899 but not on the scale of the Great Storm. Maybe the song is just a combination of all of these rather than the reference to a single event.