Detective Sergeant Dave Elcock of the East Sussex Safeguarding and Investigation Unit, said; "Wilmer systematically groomed these vulnerable victims over time and took advantage of their vulnerability for his own gratification.
"We will always take seriously and investigate such allegations. If you wish to report any offence, against you or someone you know, please contact us online or by calling 101, and arrange to talk in confidence to experienced investigators."
For the rape Wilmer was given 16 years plus a further five years on extended licence. He received eight years for each of the six counts of sexual assault offences, to run concurrently.