Figures reveal that a third of the 2,310 rape cases referred to the Crown Prosecution Service (CPS) between April and September of last year saw charges brought.

In 2013-14, the rate was 62 per cent.

The lower prosecution rate has prompted the Home Office to launch a comprehensive review into how rape cases are dealt with across the criminal justice system.

The review will look at “why there have been reductions in volumes of police referrals, CPS charges, prosecutions and convictions for rape and serious sexual assault cases”.

The data show that an increasing proportion of cases have been “administratively finalised”, meaning suspects are not charged following a review of the case paperwork.

Nearly a quarter of all cases were subject to this process in the first six months of 2018-19, compared with six per cent five years ago.

And in the past year, the number of administratively finalised cases has doubled. The increase coincides with a policy change that has seen police encouraged by the CPS to seek “early investigative advice” on whether a prosecution would likely succeed at trial.

Such advice is intended to “ensure the early development of a joint strategy for the prosecution where they would benefit from CPS expertise and advice”.

A spokesperson for the CPS said: “We want to reassure anybody affected by rape that where there is sufficient evidence for us to prosecute, we will not hesitate to do so.”

They added: “The increase in digital evidence means charging decisions are taking longer to complete. We now advise police at an earlier stage to build the strongest possible cases for prosecution. We can pass files back for further work but this does not necessarily mean the case is at an end.”