The Metropolitan Police has also been asked to launch an inquiry into claims Boris Johnson ’s top aide flouted regulations by leaving his home “without reasonable excuse” while family members showed symptoms.
Lawyers for former North West regional prosecutor Nazir Afzal, whose brother died from coronavirus, have written to both forces urging them to investigate further.
They have also sent a letter to the Crown Prosecution Service asking it to play a “proactive role” in considering relevant evidence.
Mr Afzal, who has already threatened to bring a private prosecution on behalf of the public, said: “I am concerned that the police and prosecutors have not received all relevant information and that their decision making will be incomplete as a result.
“I am troubled that previous correspondence from people including MPs has gone unanswered. Public confidence is damaged as a consequence.
“We have already had new information from reliable sources that reflect poorly on everybody who has considered the allegations thus far, including the likelihood that there are other relevant events.”
Public trust in the Government was dented as a result of Mr Cummings’ actions however the PM has stood by his senior advisor over the affair despite calls from Tory MPs for him to stand down.
In their letter to Durham Police, Mr Afzal’s lawyers wrote: “We understand that you have undertaken a short, narrow investigation into three matters and given your views on whether they constituted a breach of the regulation.
“However, it appears that not all of the relevant evidence relating to those matters has been gathered. Further, a number of other alleged breaches of the regulations which occurred in Durham do not appear to have been investigated at all.”
The three matters are believed to be references to Mr Cummings self-isolating at his parents’ home near Durham, a family day-trip to Barnard Castle on which he claimed he was “testing his eyes” and an alleged second visit to the North East on April 19.
Durham Constabulary found in June that the senior advisor may have broken lockdown regulations but decided not to take any further action
The lawyers Hodge, Jones and Allen have also written to the Met Police calling for it to investigate his actions in London, which are not thought to have been looked at by the Durham force
Mr Cummings has denied any wrongdoing and has refused to apologise for breaking at least the spirit of the guidance which millions of Brits followed rigidly
No 10 declined to comment.