If events aren't run at least once every five years I think they should be discounted. I therefore believe the two longest standing world records are as follows.
24 Hours - Walking.
Hew Neilson (GB). 133 Miles 21 Yards. 1960.
Still standing after 43 years.
100 Miles - Running.
Don Ritchie (GB). 11:30:51. 1977.
Still standing after 26 years.
Both events are still held at least once a year.
