A senior doctor who raised suspicions about Lucy Letby has said he should have gone to police sooner.
Dr Stephen Brearey was the lead neonatal consultant at the Countess of Chester Hospital when the nurse murdered seven babies and attempted to murder seven others.
In his first interview since the publication of the Thirlwall Inquiry report into what happened, Brearey reflected on the effect on staff and said he had "naively" assumed senior managers would respond to suspicions about the nurse's involvement in a series of baby deaths.
The inquiry found a "toxic negativity" within the NHS that continued to discourage staff from speaking out, despite stronger whistleblowing guidance, and said regulation was lacking.
Brearey claimed his warnings about Letby were repeatedly ignored by bosses at the hospital, which is now under new management - and also fears cultural change at the NHS will take time to implement.
"I was naively thinking that raising concerns with senior managers, they had the same values that I did and, once they got it, they would be thinking the same way," he said.
The doctor led a group of seven consultants who shared the same concerns about Letby.
Hospital bosses carried out a series of internal reviews into increased infant mortality in 2015 and 2016, but Cheshire Police was not asked to investigate until May 2017.
Letby remained employed at the hospital until her arrest more than a year later.
"I think one of the reasons we got through this and ended up picking up a police investigation is that the seven of us stuck together," he said.
"But obviously in retrospect, clearly, if we'd known what was ahead of us, we would have gone to the police earlier."
Letby was eventually arrested in July 2018 but, in the aftermath, Brearey said there "wasn't any psychological support" for staff.
"It really was the team looking after the team, and colleagues looking after colleagues," he said.
"It's a bit akin to a soldier in a battle with PTSD being taken out of the battle zone to recover, and yet the staff on the neonatal unit were still coming back to work and being re-traumatised.
"If they had to stabilise a sick baby, you can understand the triggers that might elicit, and the personal costs to staff who are parents dropping the kids off to school, and not wanting to talk to other parents."
Chairing the inquiry, Lady Thirlwall made 17 recommendations, including CCTV for all cots and incubators in neonatal units, restricted access to insulin, mandatory safeguarding training for staff, a harmonised NHS IT system and improved data handling.
Asked whether the measures would have prevented Letby from carrying out her crimes, Brearey said: "It certainly would have either prevented or hastened an alarm to say things need to be looked at in more detail.
"I think all the suggestions are very sensible and if they are all enacted then they'll go a long way towards preventing further incidents on neonatal units and elsewhere in hospitals."
Brearey also gave his thoughts about his hopes for wider cultural change in the NHS in the wake of the inquiry, but indicated he remained sceptical about the speed of change in some areas.
He said Lady Thirwall had recommended "the uncontroversial duty of every manager to put patients first".
"It feels a bit of a sad indictment on the organisation when that has to be written down into the contracts of senior managers," he said.
"It's one thing writing into a contract is another thing actually enacting it into the entire organisation and that takes a cultural change and cultural changes take time, and I very much hope that the NHS and the Department of Health can make that turnaround effectively.
"But it doesn't feel like something that's going to happen overnight to me, certainly, no."
In a joint statement issued after the publication of the inquiry report, former Countess of Chester Hospital executives Tony Chambers, Ian Harvey and Alison Kelly, along with former HR director Sue Hodkinson, said: "We are carefully reviewing the Thirlwall report and its recommendations.
"Given that there are a number of investigations under way, and that the work of the Criminal Cases Review Commission has not yet completed, it would be inappropriate for us to offer any further comment at this time.
"Our thoughts remain with the families affected by the tragic events that took place at the Countess of Chester Hospital."
In a statement given after the conclusion of the inquiry, the hospital trust said: "We know that no apology or action can undo what happened at our hospital.
"We are however truly sorry for the events that occurred in 2015 and 2016. We acknowledge the findings of the Thirlwall report and will approach its recommendations with openness and a firm commitment to build on the progress we have already made in improving our hospital's governance, safety and culture since that time.
"We are a different organisation today with new leadership, stronger governance and safety processes, and a more open culture where speaking up is encouraged and acted upon."