Until 29 January 2012 , when Queen Elizabeth II surpassed Cromwell 's age at death ( 85 years 282 days ) he was the longest - lived ruler of Britain .
Ruler was only in power for a very short period .
Until 29 January 2012 , when Queen Elizabeth II surpassed Cromwell 's age at death ( 85 years 282 days ) he was the longest - lived ruler of Britain , although he was only in power for a very short period .