A scientist has been suspended after his misconduct while working for the East and North Herts NHS Trust, which runs Stevenage’s Lister Hospital, meant 10,000 cervical smear slides had to be rechecked and 600 women recalled.

Stephen King began working as a biomedical scientist in the cytology department – where cells from the body are examined under a microscope – in 2009, and became manager there in 2013.

In February 2014, a colleague raised concerns about the quality of the staining of the slides, which affected the ability to identify correctly any abnormalities, but Mr King said “staining at the present is fine”.

Slides submitted for an independent quality assurance process were withdrawn by Mr King, but a retrospective assessment found issues with the staining of cervical smear slides between January and April 2014.

Mr King had improperly permitted a change in the agent used to stain the slides, replacing Harris haematoxylin with Mayer’s haematoxylin.

The change was due to a depleted supply of Harris, but witnesses said it could have been borrowed from another laboratory.

On Friday, a hearing by the Health and Care Professions Tribunal Service concluded that Mr King’s actions amounted to misconduct and he was suspended for 12 months.

The judgment said: “The findings of the panel are of the utmost seriousness.

“It was necessary to review in excess of 10,000 slides that had been screened, and in excess of 600 women who had undergone smear tests had to be contacted for further smear tests to be carried out.

“The recall exercise would have caused the women concerned considerable anxiety and distress.”

The panel said Mr King’s actions increased the risk of malignancy being missed and that not all patients recalled attended for further tests.

Mr King, who was absent from the hearing and no longer works for the NHS trust, has previously said he has no memory of the events.

The panel found no evidence of him showing any meaningful insight into his shortcomings, or the consequences of his actions, and said there is risk of repetition unless he acknowledges his failings.

The panel said Mr King’s suspension will be reviewed before it ends and, without positive engagement, he can expect to be struck off.

A spokesman for the NHS trust said: “The trust notes the decision reached by the Health and Care Professions Tribunal Service following its hearing into the conduct of a former member of staff, Stephen King.”