Unfit: Lord Janner, pictured in August, will not have to face trial on child sex charges after a judge ruled he could not enter a plea

Lord Janner will not have to stand trial for historical sex offences in person after a judge officially declared him unfit to plead today.

The Labour peer and former MP is accused of a string of sex attacks on young boys, allegedly carried out between the 1960s and 1980s.

A judge at the Old Bailey today ruled that the 87-year-old cannot enter a plea because he suffers from advanced dementia which means he cannot understand what is happening.

Instead, Janner will face a 'trial of the facts', due to begin next year, in which a jury will decide whether his alleged victims are telling the truth.

He also faces a £2.5million claim from six of his alleged victims who say he attacked them while they were living in Leicester care homes.

The peer, who is on leave of absence from the House of Lords, was not in court to hear the ruling by Mr Justice Openshaw.

The judge said: 'The defendant is not and never will be fit to plead or to stand trial.

'The medical opinion is all the same way - the inevitable and inescapable conclusion is the defendant has advanced and disabling dementia which is deteriorating and irreversible. Accordingly I find he is unfit to plead and be tried on the indictment.'

He said 'eminent doctors' who specialise in dementia and memory loss have assessed Janner repeatedly.

The peer does not recognise his own family, has no memory of his political career, and cannot read a book or watch the television, the judge said.

He needs a full-time carer and does not understand the charges against him, according to the four medical experts who have assessed him.

Politician: Janner's alleged crimes date back to his time as MP for Leicester West between the 1960s and 1980s

Janner can 'hardly speak, often making inappropriate and repetitive statements', Mr Justice Openshaw added, saying that this meant he could not be interviewed by police.

'He is often bewildered by simple requests - the defendant has a very severe impairment of language', the judge said. 'He can't understand the charges against him or give any account or answers to them. Utterances are reduced to a few stereotypical phrases.'

Both the prosecution and the defence had previously agreed that Lord Janner was too ill to enter a plea during a hearing in October.

When he attended a previous hearing in August, Lord Janner was visibly confused and said to his daughter, 'Oh, this is wonderful,' as he entered the court.

Director of Public Prosecutions Alison Saunders originally declined to prosecute the politician, MP for Leicester West between 1970 and 1997, on the grounds of his mental incapacity.

On trial: In this court sketch from August Lord Janner and a family member appear at Westminster magistrates' court, London for a 59-second hearing

However, she reversed her decision after a public outcry, and decided to allow a trial of the facts to go ahead.

Janner, who lives in North London, is charged with 13 counts of indecent assault on a boy under the age of 16 and nine other sexual offences against men and young boys, all dating between 1963 and 1988.

A provisional trial date has already been set for April 11 next year at the Old Bailey, while the next hearing will take place on March 7.

Civil proceedings against Janner in the High Court were recently adjourned to await the outcome of today's Old Bailey hearing.

Mr Justice Openshaw suggested the public had been 'unjustifiably sceptical' over the case, but added that they still had a 'right to know' how he came to his decision.

Decision: A judge sitting at the Old Bailey, pictured, ruled that Janner will face a 'trial of the facts'

THE KEY DATES IN LORD JANNER'S ONGOING LEGAL CASE January 2013 Leicestershire Police launch Operation Enamel – the fourth investigation into child sex abuse allegations against Labour peer Greville Janner. More than a dozen alleged victims came forward to say he had molested them, most in Leicester care homes during the 1970s and 1980s. February 7, 2013 Janner speaks for last time in Lords, giving a 765-word speech on Israel. November 26, 2013 Votes in House of Lords for the last time, on a finance bill. Claims expenses. December 2013 Police search Janner's North London home. Makes last 12 Lords appearances. April 2014 After police request to speak to Janner, medical experts send report saying he is not fit to be interviewed because he has dementia. June 2 & 3, 2014 Uses Westminster car park again and confirms to the authorities that he was there on official business, despite Parliament not sitting at the time. October 13, 2014 Janner takes an indefinite leave of absence from the House of Lords. April 16, 2015 DPP Alison Saunders says police have enough evidence to charge Janner with 22 offences, but will not do so as he is unfit to stand trial. Police and alleged victims are furious – sparking four separate reviews and threats of legal action. June 26, 2015 DPP's decision is overturned and Janner is told he faces court. August 7, 2015 Janner fails to appear in court and is threatened with arrest. August 14, 2015 Janner appears at Westminster magistrates' court for a 59-second hearing in which he does not appear to understand what is happening. November 27, 2015 Preliminary High Court hearing into the civil case launched by six of Janner's alleged victims, who are seeking £2.5million in damages. December 7, 2015 Judge rules that Janner is not fit to stand trial and will therefore face a trial of the facts instead. Advertisement

Professor Michael Kopelman, of the University of London, was first asked to advise the prosecution on whether Janner was able to answer police questions.

On February 19, 2014, he reported that the defendant could not name his children or grandchildren, or remember where he had been to school or to university.

He had a very poor short-term memory, was forgetful of names and objects and became lost if unaccompanied, the court heard.

The judge said: 'The prognosis was for an inevitable, progressive and irreversible degeneration which would end only with his death.'

A year later, Professor Kopelman advised that 'Lord Janner would be unable to understand the charges against him, to comprehend that a juror could be challenged, to instruct his lawyers, to comprehend the details of evidence, or to follow and recall the court proceedings'.

On August 25, Dr James Warner, for the defence, issued another report detailing how Janner slurred his words and appeared 'perplex'.

Describing the report, the judge said: 'He exhibited a condition known as "logoclonia", being the repetition of simple words. He then had only a limited vocabulary.

'Most of his answers were inappropriate to the questions asked, indeed, he gave virtually no coherent answers to the questions asked.

'He was often bewildered by simple requests, even when made in simple language and given repeatedly.'

Dr Norman Poole, also for the defence, reported in August that Janner's Alzheimer's was 'advanced'.

He concluded: 'The defendant is now at an advanced stage of dementia. All his cognitive functions are impaired, particularly his memory and language functions and consequently, he is unfit to plead.'

Dr Kate Humphreys, for the prosecution, saw the defendant in September and reported that his utterances were 'now reduced to a few stereotyped phrases' and he was largely 'incomprehensible', the judge said.

In his final report of September 21, Prof Kopelman gave an account of the defendant's daily regime.

Quoting from his report, the judge said: 'He can now hardly speak, and when he does it is often only to make inappropriate repetitive statements.

'He can no longer read a book or follow the television, so he no longer watches. He scarcely recognises his own family and has entirely lost even his short-term memory. He is now unable to give any meaningful account of any aspect of his personal or professional history.