Robin Woodrow-Gill pleaded guilty to eight sexual offences against children as young as three, carried out between 1958 and 2013.
At Truro, UK Crown Court Judge Christopher Harvey Clark said he had perpetrated "pernicious evil".
Woodrow-Gill, from Torpoint, Cornwall was jailed for 10 years and put on the sex offenders register for life.
The judge said: "You are a paedophile and you have had a lifetime's sexual interest in young children.
"You first showed it when you were aged 18. Although you are now 73 that perverted interest has continued."
The judge said victims' lives had been "shattered" by Woodrow-Gill's offences.
During sentencing, the judge referred to the case of disgraced celebrity publicist Max Clifford and said penalties for crimes committed many years ago did not "reflect modern attitudes towards child abuse".
Woodrow-Gill was sentenced to four years for a 2013 sexual assault on a child, with consecutive sentences of one year each for three offences of indecency with a child, committed between 1982 and 1992, and three offences of indecent assault on a child during the same period.
He was sentenced to 16 months to run concurrently for an offence of indecent assault on a child committed between 1958-59.
There is that cursed concurrent sentencing again. WHY? WHY? WHY?
This man should never get out of prison vertically! What is with that?