Labour peer Lord Greville Janner will be prosecuted over claims of historic child sex abuse after an independent review overturned a decision by the Crown Prosecution Service (CPS).

Lord Janner, whose home in West Heath Road, Hampstead, was raided by police investigating the allegations in 2013, has now been charged with 22 child sex offences, alleged to have taken place between 1963 and 1988, which will be considered at a preliminary hearing at Westminster Magistrates’ Court on August 7.

In April, director of public prosecutions (DPP) Alison Saunders announced that Janner, 86, would not face trial over allegations he abused children in Leicestershire children’s homes in the 1970s and ‘80s because he is suffering from Alzheimer’s disease.

But today the CPS announced that criminal proceedings would be brought against the former Leicestershire MP following an independent review of the DPP’s original decision was called for by alleged victims.

The review, led by barrister David Perry QC after calls from six of the complainants, concluded that it was in the public interest to bring proceedings before a court.

Ms Saunders had previously ruled that it was not in the public interest to prosecute because medical evidence showed that Lord Janner was not fit to stand trial.

In a statement announcing the reversal of her decision, she said: “I have always said that in my view this was an extremely difficult and borderline case because of the strong arguments on both sides.

“I have also always emphasised my concern for the complainants in this case. I understood their need to be heard, which is why I contacted Justice Goddard to ensure that they could give evidence as part of the public inquiry.

“However, the review has concluded that this forum, albeit a public one, cannot substitute for the adjudication of the courts. I accept the outcome of the review and will now be bringing this prosecution to allow for that adjudication to happen.”

It is now likely there will be a “trial of the facts” after the preliminary hearing at Westminster Magistrates’ Court.

The CPS is expecting Lord Janner to be found unfit to stand trial which would mean a jury would be asked to consider whether he was guilty of the alleged acts after hearing prosecution submissions, as well as a test of the prosecution case by a defence team.

However, the jury would not be asked to return guilty or not guilty verdicts but to say whether they find the acts to have been done.

If they are satisfied the acts were done, there are three options available to a judge: a supervision order, a hospital order or an absolute discharge.

If they are not satisfied then Lord Janner would be acquitted as with a normal trial.

The review of Ms Saunders’ decision was brought through the victims’ right to review scheme, which was introduced by former DPP Sir Keir Starmer, now Holborn and St Pancras MP.

Responding to claims that Ms Saunders should resign after her judgement was reversed, Sir Keir said: “I would far rather have a DPP who subjected her decisions to review than a DPP who refused to have her decisions tested. This is not a resigning matter.”

When announcing her original decision in April, Ms Saunders was critical of the CPS and police for failing to prosecute in the light of previous allegations made against him in 1991, 2002 and 2007.

The peer, who has been suspended by the Labour Party, was MP for Leicester North West and then Leicester West for 27 years.

His family insist he is innocent of all charges.