The South London and Maudsley Trust is struggling to recruit the nurses and midwives it needs, NHS Digital data shows.
The Royal College of Nurses has warned that both aspiring and experienced nurses are leaving the profession, as a result of pressure on the workforce.
The latest figures show that 911 nursing and midwifery job openings were advertised by the South London and Maudsley NHS Trust between October 2017 and September 2018.
As of September, the trust employed 4,294 full-time staff, with 30% of them in nursing and midwifery – but these roles made up 48% of the positions advertised over the year.
Doctors and dentists, meanwhile, represented 10% of staff and 6% of vacancies.
Overall, 1,879 jobs opened up at the South London and Maudsley Trust over the year.
RCN England director Patricia Marquis said underfunding and a lack of planning has severely depleted the nursing workforce.
She said: “Our members say they’ve been pushed from pillar to post. They feel anxious that they might make mistakes because of the constant pressure short staffing causes.
“The burden on the insufficient workforce leads to conditions in which experienced nurses consider leaving, and aspiring nurses think twice about their chosen career.”
She added: “Shortages don’t just make every hard-working healthcare worker’s job more taxing and arduous. It has a clear impact on the safe and effective care of patients.”
The RCN urged politicians to provide more funding for higher education in nursing and introduce legislation to crack down on unsafe staffing levels.
Across all trusts in England, just under 350,000 vacancies were posted over the year, with nearly 150,000 of them in nursing and midwifery.
Nursing staff make up 30% of the national workforce, but 42% of vacancies.
A Department of Health and Social Care spokesperson said: “Record numbers of dedicated NHS staff work tirelessly to make sure patients get excellent, safe care.
“We are supporting them by opening 25% more training places for doctors, nurses and midwives, giving a significant pay rise to over 1 million staff, and listening to the issues that matter to them.”