[caption id="attachment_106965" align="alignleft" width="224"] Ralph Clarke [/caption] LONDON — A 101-year-old man, who last week became the oldest Briton to be convicted of a criminal offence, was jailed for 13 years on Monday for a string of historical sex crimes against two young sisters and their brother. Retired truck driver Ralph Clarke was found guilty of raping and abusing the sisters in the 1970s and early 80s, having earlier admitted indecently assaulting their brother and attempting to rape him when he was a schoolboy. He was jailed for 13 years at Birmingham Crown Court after being convicted of more than 20 charges. Police said Clarke was the oldest person to have been found guilty of a crime in British legal history and prosecutors said the severity of his offences meant that he should face action despite his age and frail condition. Clarke had abused the girls, who were aged between four and 13 at the time, at his home in Birmingham, central England, in the cab of his work truck and in his garden shed. He also assaulted the brother on numerous occasions. His victims finally contacted police in August last year having seen Facebook posts celebrating Clarke's 100th birthday.