John Tinniswood was born in Liverpool, Merseyside, England, UK, on 26 August 1912.

Due to problems with his eyesight, he was given an administrative role with Royal Army Pay Corps during the Second World War. In addition to accounting and auditing, his work involved logistical tasks such as locating stranded soldiers and organizing food supplies. During his time in the army, he met his wife, Blodwen, at a dance in Liverpool. The couple married in 1942, and their only child, Susan, was born in 1943. The couple were married for 44 years until Blodwen died in 1986.

Prior to his retirement in 1972, Tinniswood worked as an accountant for Shell and BP. He has been a lifelong fan of Liverpool FC.

In 2019, he told The Mirror that fish and chips were his favorite dish. After being recognized as the world’s oldest (known) living man, he commented that the secret to his long life is “pure luck.” He was unfazed by his newfound status, stating, “It doesn’t make any difference to me, not at all. I accept it for what it is.” At that time, he was still able to perform most daily tasks independently – he got out of bed unassisted, listened to the radio to keep up with the news, and still managed his own finances.

Tinniswood currently lives in a care home in Southport, Merseyside, England.