Unison said an overwhelming majority of the 37 phlebotomists voted for strike action in an industrial ballot that will see them walk out from midnight on Monday 17 March.

The union says it requested that Gloucestershire Hospitals NHS Foundation Trust resolve the dispute over a year ago, but ‘the trust has failed to act'.

Unison claims the trust has incorrectly calculated the phlebotomists' pay, leaving them on Band 2 of the NHS Agenda for Change pay scale, despite their skills, knowledge, and the complex nature of their work warranting Band 3 pay.

The NHS employees are paid £12.08 an hour despite their expertise and vital role in patient treatment, with some having worked in the NHS for more than two decades, said Unison.

Unison South West regional organiser, Chris Roche, said: ‘These dedicated staff play a vital role in our national health service. They should be allowed to focus on their patients, rather than worrying about whether they can pay their bills.

‘NHS staff want to be at work giving patient care. The trust can still do the right thing to prevent the disruption this strike will cause.'

In response, trust chief executive Kevin McNamara, said: ‘In response to planned industrial action from midnight on Monday 17 March, contingency planning is underway with the aim of maintaining service continuity as much as possible. We are advising patients to access hospital services in the usual way unless they hear from us directly to advise otherwise.  

‘We will continue to work closely in partnership with our local union representatives and phlebotomists on resolving this issue.'