Whitlock, who ran as a teenager and took up the sport again in his forties, first became the oldest person to run a marathon in less than three hours in 2000, at the age of 69, with a time of 2:52:47.

At 73, he set a world record in the marathon for men 70 to 74, running a 2:54:48, his fastest time after turning 70.

[3][4] In the rescheduled 2021 London Marathon, Mike Sheridan of Newbury AC joined this list by running 2:59:37, which he bettered in 2023 to 2:59:13.

While at school and university in England, he was a serious junior runner, primarily at cross country but also at track and road relays.

[5] In his sixties after retiring he started to concentrate on road racing and latterly the objective of becoming the first man over 70 to run a marathon in less than three hours.

In the following year, he lowered the record to 2:54:49 and in 2005 ran 2:58:40 at age 74, making him the oldest man to run under three hours for a marathon.

[11] On October 16, 2016, Whitlock, aged 85, ran the Toronto Marathon in 3:56:38, setting a new world record.