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."
More top news
Mezzo-soprano Katherine Jenkins will join this years’ headline acts at Latitude festival in Suffolk.
After a cold start with some bright and sunny spells it will cloud over with rain expected in the afternoon.
There's been an increase in the number of hate crimes in Bedfordshire prompting a police pledge to crack down on the crime.