Rape is already under-investigated and under-prosecuted in the UK, and we've seen numbers of prosecutions declining alarmingly after the cases that caused this new guidance to be issued.
So we don't need to wonder, we know: police and CPS administratively close the case.
Can you share the data that show the numbers of prosecutions declining per reported case, before and after the new guidance was issued?
As a comparison, I am reminded of Swedish statistics. Both people being assaulted in the home and sexually assaulted shared the same clearing rate. If rape is under-investigated in the UK we should expect those data to look very different unless both crimes are under-investigated, in which case I must ask what the norm is for which the claim of under-investigated is based on.
The claim for under-investigation comes from the fact that in English law rape is a very serious offence, and carries a similar sentence structure as murder. There are 150,000 rapes per year (according to the annual crime survey, which probably under-counts rape) and there are only 5,000 prosecutions each year.
So we don't need to wonder, we know: police and CPS administratively close the case.