The region’s ambulance trust plans to appeal a court decision in which staff won a landmark victory over holiday pay.
The Court of Appeal on Monday found in favour of paramedic Neil Flowers and 12 of his colleagues who all work for East of England Ambulance Trust (EEAST).
The ambulance staff - who work across Norfolk, Suffolk, Essex, Cambridgeshire, Hertfordshire and Bedfordshire - argued their holiday pay should better reflect the hours they actually worked, and should be calculated including overtime rather than be based solely upon their contracted hours.
It means NHS staff who do overtime on a regular basis or frequently work beyond their normal shifts should now have these extra hours taken into account when their holiday pay is worked out.
But an EEAST spokesman said: "We are not satisfied with the interpretation of the law in either of the judgements made. We remain concerned at the impact these decisions could have both on ourselves and other NHS employers, and we have instructed our legal representatives to appeal to the Supreme Court on both judgements."
Union Unison, which took the case to the Court of Appeal after winning employment tribunal and employment appeals tribunal cases in May 2017 and April 2018, said chronic staffing shortages across the NHS mean that health workers regularly do overtime, both to ease pressure on their colleagues and boost their own pay.
You may also want to watch:
And the union said the government's failure to recruit and retain enough people to sustain the NHS means that working overtime has become the norm for increasing numbers of staff.
The ruling could benefit tens of thousands of NHS staff employed under the Agenda for Change payment system and is in line with earlier legal cases, which established that workers should receive the same wages on leave as they do when working. Only doctors, dentists and senior managers will be exempt from the change.
Unison general secretary Dave Prentis said on Monday: "Before this judgment NHS workers who did regular overtime or often worked well beyond their shifts saw a drop in their pay whenever they took a well-deserved break.
"Leave calculations that weren't based on the extra shifts and hours they did week in and week out meant many were considerably out of pocket.
"Unison always believed that the rules around NHS pay already allowed for overtime and working beyond the end of a shift to be taken into account when calculating holiday pay. This judgment confirms that but does highlight another pressing problem.
"The NHS urgently needs to recruit more staff so existing nurses, paramedics and other health workers don't have to regularly work overtime simply to keep the service afloat.
"This is a victory for all those health service workers who regularly go the extra mile to make sure we receive the best care possible at all times of the day and night."
More than 100 other cases were stayed pending the result of this judgement. However those may now face a longer wait as the trust said it would be appealing and added: "As a trust we are committed to offering our staff good rates of pay, a generous holiday entitlement and great working conditions."