He'll be in a vulnerable prisoner wing so highly likely he won't come into any contact with the average prisoner. All the same, best he doesn't go anywhere near somebody with a boiling kettle and an empty sugar bag. Being in his 80's having had a fairly soft and priviledged life he's going to have to be that fast a learner.
The sentence looks lenient because he has the 'good fortune' of having been convicted for crimes committed before the mid 80's. It was only around 1985 that courts and politicians began to take child rape and kiddy fiddling seriously. He can only be tried and convicted for the crimes of the day, with the punishments of the day. Sex with a minor back in the 70's could only be worth 2 years (out in 11 months), so the judge has wrapped up pretty much the maximum he could give hime without danger of an appeal.
He'll serve 33 months by current tariffs, with the slight difference that as a sex offender he'll have to admit to his crime and get therapy to be considered for such an early release. 33 months inside for someone in their 80's, he might not come back out. Not least, as they are now considering further charges.