Distinctive similarities between alleged sexual assaults on boys by Sir Edward Heath helped convince police that they would be justified to question him under caution were he alive today, according to a leading human rights lawyer.

Officers found ‘important idiosyncratic corroborating’ evidence against the former Tory Premier which was ‘clearly not the product of collusion’ in cases spanning nearly 50 years and across Britain.

Danny Friedman QC saw secret evidence obtained by police investigating Sir Edward, who died in 2005.

Distinctive similarities between alleged sexual assaults on boys by Sir Edward Heath helped convince police that they would be justified to question him under caution were he alive today, according to a leading human rights lawyer

Mr Friedman, who was a ‘scrutineer’ of the Operation Conifer inquiry into Sir Edward by Wiltshire Police, also defended the conduct of the force’s Chief Constable, Mike Veale.

Mr Veale was ‘passionately’ determined to get the inquiry right and led it with ‘rigour, fairness and fearlessness’, said Mr Friedman.

Emphasising the scale of the inquiry with 42 allegations involving 14 forces, he said: ‘Of itself, that tells you something about the nature of the task, but also that the complaints emerged from different parts of the country, from people who were largely unconnected.’

It explained why the inquiry concluded ‘there were reasonable grounds to suspect that offences had been committed’ by Sir Edward in seven cases.

Danny Friedman QC (left) saw secret evidence obtained by police investigating Sir Edward, who died in 2005. Mr Friedman, who was a ‘scrutineer’ of the Operation Conifer inquiry into Sir Edward by Wiltshire Police, also defended the conduct of the force’s Chief Constable, Mike Veale (right)

Police had taken account of the ‘credibility, character and vulnerability of the alleged victim, potential motive to deceive and risk of inadvertent error’.

They had studied ‘similarities in accounts to rule out the risk of collusion between complainants and to spot mutually corroborating idiosyncratic details that were important, precisely because they were not the product of prior collusion.’

Last week's Mail On Sunday report

Mr Friedman said: ‘In legal terms Sir Edward must be presumed innocent but after a process of investigation there would have been reasonable grounds to invite him to comment.’

He denied that Mr Veale had ‘lost control’ of the inquiry and that it did not simply ‘sleep walk’ into saying Sir Edward would be treated as a suspect. ‘It got there through a careful, albeit fearless, investigation.’

Mr Friedman rejected claims that the inquiry was ‘pointless’ as it was unable to say if Sir Edward was guilty.

The Mail on Sunday last week reported that Dr Elly Hanson, a leading expert on child sex abuse who took part in the investigation, said she would not have trusted him with children.