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
Over 740,000 adults aged 40-60 in our region do not achieve ten minutes of continuous brisk walking over the course of a month.
Six people - aged between 16 and 28 - have been arrested over two stabbings in Newmarket earlier this week.
The NSPCC is referring a record number of reports of neglect to police and social services - including a massive increase from this region.