The coroner at the inquest into the death of Dawn Sturgess will request turning the investigation into a full public inquiry, after her counsel accused the Home Secretary of not engaging “more constructively” with the process.

The Royal Courts of Justice heard how coroner Baroness Heather Hallett previously requested Priti Patel’s provisional view on whether the inquest into the death of the mum-of-three three years ago could be widened to a public inquiry to better examine Russian involvement.

But Ms Patel declined, stating it would be “inappropriate” to do so in advance of a formal request. Lady Hallett said she would now write to the Home Office doing just that, with confirmation expected by the end of this year.

Any public inquiry is unlikely to start before 2023, and will be held partly in private for security reasons.

Read more: Dawn Sturgess inquest: Why deciding scope was controversial

Announcing her decision, the coroner said: “As set out in my letter to the Secretary of State for the Home Department, I have firmly concluded that I cannot conduct a full, fair and effective inquest into the death of Dawn Sturgess if these proceedings continue as an inquest.

“I have seen substantial material that is far too sensitive to be made public, even in gisted form.

“I have no option, therefore, but to request the Secretary of State convert this inquest into an inquiry and I invite her to consider my request as a matter of urgency.”

She added: “I do understand the difficulties in Government… but I really do hope the Secretary of State can respond within the timescale considered.”

Cathryn McGahey QC, for the Government, said Ms Patel would “very much aim to make a decision” by Christmas.

The coroner said she would request Ms Patel’s reply within two months.

Outlining the correspondence between the coroner and the Home Secretary at Wednesday’s pre-inquest hearing, Lady Hallett’s counsel Andrew O’Connor QC said: “It is a matter of considerable regret that the Secretary of State (Ms Patel) has not engaged more constructively with the coroner’s request.

“Since you have now reached the clear view as to the need for an inquiry, it would have assisted all involved to know the Home Secretary’s provisional view on this issue.”

Mr O’Connor told the coroner that it appeared the Home Office considered Lady Hallett’s request for Ms Patel to read the case documents in order to inform her provisional decision was a task deemed “too burdensome – despite the fact that the reports took you only a few hours to read”.

Adam Straw QC, representing Ms Sturgess’ family and her partner Charlie Rowley, backed the call for a public inquiry.

He said: “Their overriding concern is to ensure the truth of how Ms Sturgess died is established.

“No family should wait five-and-a-half years to find out how someone died.”

His colleague, Michael Mansfield QC, said the prospect of a criminal trial on the poisonings was “infinitesimal”, and so said a public inquiry represented the best way of finding out what happened.

The inquiry – if granted – would likely be held in both Salisbury Guildhall and at venues in London.

On Tuesday, the Metropolitan Police named Denis Sergeev, who used the alias Sergey Fedotov while in the UK, as the third Russian spy to face charges over the poisonings.

Read more: Third Russian spy accused of attempted murder over Salisbury Novichok attack

Sergeev is accused of seven charges, including three of attempted murder – former Russian spy Sergei Skripal, his daughter Yulia and ex-police officer Nick Bailey – as well as conspiracy to murder Mr Skripal, causing grievous bodily harm with intent to Ms Skripal and Mr Bailey, and possession and use of a chemical weapon.

These are the same counts faced by two other suspects in the case already identified by police three years ago, Alexander Mishkin, who used the name Alexander Petrov while in the UK, and Anatoliy Chepiga, who used the alias Ruslan Boshirov.

Petrov and Boshirov previously denied any involvement in the plot and gave a much-derided interview to state television in which they said they were only in Salisbury for a sightseeing tour of the cathedral.

The Skripals were left fighting for their lives in March 2018 when Novichok was smeared on Mr Skripal’s door handle in Salisbury, Wiltshire.

Mr Bailey was one of the officers investigating the case and also became seriously ill.

Ms Sturgess, 44, died in hospital on July 8 that year and her partner Mr Rowley became seriously ill in Amesbury, after they also came into contact with the substance on a perfume bottle.

A further pre-inquest review will be held in December.

Get more Salisbury news. 

You can also like our Facebook page and follow us on Twitter and Instagram to stay up to date.

If you want online news with fewer ads, unlimited access and reader rewards - plus a chance to support our local journalism - find out more about registering or a digital subscription.

Email newsdesk@salisburyjournal.co.uk with your comments, pictures, letters and news stories.