If you look at what he said in full (rather than the guardian extract) you’ll see what he was trying to say. As an ex-lawyer he has some experience of rape cases in court, and sentancing is a function of severity of the crime. His crap wording was intending to make the distinction between cases with many aggravating sentancing considerations and those with fewer aggravating features.
He was also alluding to “lesser” rapes as in those that fell under statutory rape classifications where sentancing mitigation has the effect of bringing down the average sentance length for them – such as 17yr olds guilty of having sex with 15 yr olds.
If we had automatic sentancing for all rape cases regardless of aggravation/mitigation then there would be no impact on early releases. As it is we have statute that provides for proportionate sentancing in the hands of judges, THAT is what Ken was referring to when Millitwat was banging on about 15 month sentances across “rape” cases.