At of today (28th May 2012), Queen Victoria, the great-great-grandmother of Queen Elizabeth II, is the longest reigning Monarch in British history. Queen Victoria reigned from 1837-1901, which is 63 years and 216 days in total.

Comparing to her great-great-grandmother, Queen Elizabeth II became Queen on on 6th February 1952 when she was 25 years old and has reigned just over 60 years. However, at the age of 86 years old, Queen Elizabeth II is the oldest reigning British monarch.