Singer-songwriter and activist Billy Bragg has joined striking nurses on a picket line in Dorchester.
He arrived to chants of his name before launching into songs that included the lyrics "solidarity forever" and "there is power in our union".
It comes as thousands of nurses are on strike today and tomorrow at more than 55 NHS trusts in England.
This follows strike action in December and earlier this month by ambulance workers and nurses.
It has also been announced that thousands of ambulance workers and nurses will go on strike on the same day next month as the pay dispute with the Government shows no signs of reaching a resolution.
The GMB union said more than 10,000 ambulance workers, including paramedics, emergency care assistants and call handlers, will stage strikes on 6 February, 20 February, 6 March and 20 March.
Nurses are also due to strike on 6 February - meaning mass disruption can be expected across the NHS on that day. Nurses will also strike on 7 February.
Pat Cullen, Chief Executive of the Royal College of Nursing (RCN) union, said that nurses feel "totally heartbroken" at going on strike, but have no choice.
She urged the Government to get back around the table to resolve the dispute but said no talks are currently scheduled with Health Secretary Steve Barclay.
She said: "No nurse should be ashamed to say that, actually, they're really struggling to live on the meagre salaries that this Government's paying them.
"It's their right to be paid a decent wage."
She told ITV's Good Morning Britain that the NHS is not currently delivering an acceptable minimum staffing level, which "flies in the face" of new anti-strike laws calling for minimum service cover on strike days.
"Minimum staffing levels are not available for our patients or our nurses on any day of the week," she said.
"So to try and suggest that we're going to have minimum staffing levels on days of industrial action is just so far removed from reality, and in fact, it is a total insult to our patients and to nurses - it just doesn't happen.
"You cannot have minimum staffing levels with 47,000 unfilled posts. So, I do not know how this Government's going to do this."
On Tuesday (17 January), the Health Secretary signalled that pay negotiations will look ahead to next year rather than reflecting on the 2022/23 pay award, which unions have said must be reviewed.
Prime Minister Rishi Sunak's official spokesman today said: "We continue to be concerned with the level of disruption strikes bring to patient care.
"As the Health and Social Care Secretary said, we want to continue discussions. We think that is the right way forward rather than picket lines."
As the strikes got underway, the NHS reminded patients to attend all their usual appointments unless they have been contacted and to seek urgent care if needed during the strikes.
The health service is likely to be running a bank holiday-style service in many areas.
Thousands of operations and appointments are expected to be cancelled due to the strike action on Wednesday and Thursday. Almost 30,000 needed to be rescheduled following December's nurse strikes.