John Gilbert Blacktop, 81, of Marine Road West, Morecambe was found guilty in his absence of over 30 sex offences at Bradford Crown Court.
The offences, which were all committed during the 60s and 70s, included rape, attempted rape and over 30 indecent assaults.
He was cleared of one charge of indecent assault.
His victims were aged between five and fourteen at the time of the offences which were committed in Lancaster and Stockton-on-Tees.
Police are now appealing for help to find the wanted man.
Anyone with information should contact police on 101 quoting log number 0873 of March 29th.