A 101-year-old man in Britain has been convicted of sexual offences against children, becoming country's oldest prison inmate.

A jury on Friday found Ralph Clarke guilty of 21 counts of indecency and indecent assault on two girls in the 1970s and '80s. The former truck driver had admitted nine other charges against a boy.

Clarke was taken from Birmingham Crown Court in central England to prison to await sentencing on Monday. Judge Richard Bond said Clarke was facing a prison term and it would be "amazing" if he lived long enough to be released.

Emma Fennon, a detective with West Midlands Police, said some might question prosecuting a 101-year-old. But she said "those he assaulted had to live with the suffering he inflicted on them for decades."