Concerns about high death rates and waiting times at Blackpool Victoria Hospital led to enforcement action from NHS Improvement.
A document outlining health bosses' fears was sent to the hospital earlier this year, and was released to The Gazette under Freedom of Information laws.
It preceded a critical report from the regulator Care Quality Commission (CQC) and highlighted several key areas of worry, including high mortality rates, lengthy A&E waiting times, and cancer targets.
The Vic, in Whinney Heys Road, has since put a new action plan in place to reduce the number of preventable deaths and avoidable harm incidents, and improve the last thousand days of patients' lives.
An 'improvement director', Nicki Latham, has also been sent in, and will report back to national health bosses. She is expected to be at the Vic until next March.
The letter from NHS Improvement, which is responsible for overseeing the trust that runs the Vic as well as others like it, said it had "reasonable grounds to suspect" the trust "has provided and is providing health care services for the purposes of the NHS" in breach of its licence.
Specific concerns included:
- A CQC report in March last year which said the trust 'requires improvement' overall, with urgent and emergency care services deteriorating to 'inadequate' for safety and 'requires improvement' for responsiveness;
- Higher than expected death rates dating back five years, with six alerts issued by the CQC by the turn of this year;
- Too many patients being left waiting in A&E for more than four hours, with 26 left waiting for more than 12 hours in just 22 days during last winter; and
- Too many cancer patients being left waiting for more than 62 days for their first round of treatment after being referred from an NHS screening service.
"The matters set out above demonstrate a failure of governance arrangements, in particular a failure to establish and effectively implement systems and/or processes to ensure compliance with health care standards," the letter said.
The hospital agreed to a "implement the action plan that it has developed to address the concerns in the CQC inspection report", it added, and "develop a quality and performance improvement plan which will, as a minimum" say how it will tackle the issues raised.
Chiefs expected "a robust trajectory, with appropriate milestones for the delivery of key objectives to underpin recovery" - and said they would "appoint an improvement director" who will be work with the Vic to boost standards.
On Monday, The Gazette revealed how bosses at the trust will spend £750,000 on a plan to improve care over the next three years, with interviews for a new chief set to oversee the project due to be held on Friday last week.
But, several months on from NHS Improvement setting out its concerns, the Vic continues to struggle to hit some of its key targets.
It did not achieve the four-hour A&E target, which says 95 per cent of patients must be admitted, transferred, or discharged within that time, in September, scoring 85.16 per cent, according to board documents from earlier this month, though it still performs well compared to other hospitals, with the four-hour target not being hit nationally since mid-2015.
And it did not meet the 62-day urgent referral to treatment target for cancer patients, recording a hit rate of 80.7 per cent against a target of 85, in August, the papers added.
It did hit a 62-day screening target with a performance of 90 per cent against a target of 90 per cent, but failed to hit a two-week breast cancer target - scoring 91.7 per cent against a target of 93 per cent.
The hospital's new chief executive Kevin McGee, who has made a number of key personnel changes since replacing the retired Wendy Swift, said work had already been done to lower the mortality rate, which he partly blamed on wider issues like Blackpool's high levels of deprivation and low life expectancy.
The rate is "now in the expected range", he said, thanks to improvement and investment over the past six months, though he conceded there "are things the trust needs to get right".
"We can see signs of improvement but it will take two or three years to get fully on top, and get the organisation to where it should be, which is 'good' or 'outstanding'," Mr McGee said.
"What I have seen since being in post is some brilliant services and staff. They have been let down historically by some poor decisions and leadership. What I have been focused on is getting a new executive team in place. We have already seen improvement."
The CQC's latest report, which followed an inspection just weeks after Mr McGee took over, asked whether the trust is "well-led" - and gave that particular key area a rating of 'inadequate'.
The regulator said: "Immediately prior to our inspection, the chief executive retired and there was a new interim chief executive who had been in post for five weeks at the time of the inspection.
"We found insufficient priority was given to improvement work that was needed. Some executives in key roles were out of touch with what was happening on the front line and they could not identify or did not understand the risks and issues described by staff.
"We were not concerned regarding the skills and abilities of these executives recently appointed."
Several factors affect mortality rates - and the trust warned that "a higher than average number of expected deaths should not be interpreted as the number of avoidable deaths".
A spokeswoman said: "Locally and nationally there is increasing demand on NHS emergency departments and this trust is investing more than £11m in an emergency village, which will make the improvements needed to modernise our A&E department to create more space and improve patient facilities.
"Our overall figure for four-hour waiting times was 84.3 per cent last month (the national average was 85.4 per cent) and 41 patients breached the 12-hour target.
"The trust is committed to ensuring it improves the proportion of people waiting less than 62 days from urgent referral to definitive cancer treatment and an improvement plan has been developed to address cancer performance and capacity.
"The 62-day cancer target for September (the last monthly reported figures available) was 78 per cent."