Two mill managers have been cleared of health and safety offences following an explosion which killed four people.

The blast at the wood mill in Bosley, Cheshire, on July 17 2015 killed cleaner Dorothy Bailey, 62, maintenance fitter Derek William Barks, known as Will, 51, mill worker Derek Moore, 62, and chargehand Jason Shingler, 38, whose body was never recovered.

Mill manager Peter Shingler, 56, of Tunstall Road, Bosley, and operations manager Philip Smith, 58, of Raglan Road, Macclesfield, had each been charged with a health and safety offence but on Friday, following a 12-week trial, the jury was directed to return not guilty verdicts.

Their acquittal came after the jury was directed on Thursday to find mill owner George Boden and firm Wood Treatment Ltd not guilty of manslaughter charges.

Tony Badenoch QC, prosecuting, said: “Following the events of yesterday and adjournment overnight, the position has now been reached that the prosecution will not continue to seek guilty verdicts in the case of Mr Smith and Mr Shingler.”

After he was cleared of four counts of gross negligence manslaughter, Boden pleaded guilty to an offence under the Health and Safety at Work Act 1974.

Wood Treatment Ltd had admitted a health and safety offence before going on trial charged with corporate manslaughter.

No family members of the victims were in court on either Thursday or Friday to see the not guilty verdicts returned, although the hearings were being relayed on video link.

Judge Mrs Justice May said: “Members of the jury, it’s been a long trial and we are very grateful to you for your attendance and attention throughout it.”

She said they could be released from jury service for 10 years.

Following the verdicts, Detective Chief Inspector Paul Hughes, who led the investigation, said: “We understand that this will not be what the families had hoped for and that it will not take away from the devastating loss they feel.

“We know that this has been an extremely difficult time for everyone involved and we are continuing to support the families as they come to terms with the outcome.”

The manslaughter charges were dropped following an application to dismiss on behalf of the defendants at the end of the prosecution case.

In her judgment, later confirmed by the Court of Appeal, Mrs Justice May ruled there was not enough evidence to prove that gross negligence caused the explosion.

During the trial, which began in early February, the court heard the damage caused to the mill had made it impossible for investigators to determine the cause of the blast.

The prosecution said it involved an explosion of wood dust allegedly caused by negligence on the part of the company and management, who they claimed knew dust levels were excessively high.

The jury heard evidence that employees had raised concerns about safety at the mill in the years leading up to the explosion and reported “mounds” of wood dust piling up.

Sentencing of Boden and Wood Treatment Ltd will take place on June 18.