Health Secretary Andrew Lansley said that past efforts to tackle the deficit at the South London Healthcare Trust had not been successful, and that turning its fortunes around would be a "big challenge".
It is the first NHS trust in the country to be put under the control of a special administrator.
"Although there have been some improvements in mortality rates, maternity services and infection control, and some early signs of improvements in waiting times, they do not go far enough. It will be impossible for South London to build on these improvements while tackling such a large deficit....
"...I am confident that with the regime I am enacting today in place, and working extensively with clinicians, health service leaders, patients and local people, [the special administrator] will have the tools and framework in place to find a long-term satisfactory solution for the people of south east London."
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It's not just London where elections have been taking place today. There were council elections taking place across the home counties.