evidential

In his latest letter, sent to MPs, he said he was taking the "unusual" step of sharing more details because "government briefings have been provided commenting on the evidential situation".

However, last month the director of public prosecutions, Stephen Parkinson, who leads the CPS, said "the case could no longer proceed to trial since the evidence no longer met the evidential test".

Mr Cameron further told the hearing he anticipated "four to five weeks for the evidential hearings."

The CPS announced the charges against the former parliamentary researcher and teacher would be dropped early last week, as the "evidential threshold" had not been reached.

He said the families were "extremely concerned" about an evidential picture which indicated a "series of system failings, complacency, a lack of curiosity and inadequacy".