Sir David Nicholson refused to answer questions from journalists as he arrived at the NHS conference this morning.
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Around 31 people are still thought to be missing after the boat sank on a reservoir near the city of Medellin.
Bins were set on fire and objects were thrown at officers as protesters demanded justice for the death of Edir Frederico Da Costa.
Patients are being left "belittled and bewildered" as medical staff try to deal with overstretched systems, the BMA will warn.