Paul Remington vice chair of the East of England Ambulance trust thanks Ms Ball for her hard work.
He said: “Maria spent many years leading the ambulance service and I would like to thank her for her dedication and commitment through what have been some challenging times.
"Maria oversaw the formation of this Trust, bringing together three disparate organisations into one service, and its subsequent development."
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Ukip has responded to the resignation of its only MP, Douglas Carswell, by suggesting he quit before he was kicked out.
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ITV News Anglia's Political Correspondent Emma Hutchinson asks what next for UKIP after Douglas Carswell quits the party?