(CNN) Cake. Face painting. Singing. Games. Outside a National Health Service England office in London on Thursday morning were all the elements of a classic children's birthday party.
The "party-goers" were the NHS Anti-Swindle Team, a small group of activists marking NHS' 70th anniversary with a series of creative actions and stunts against the government's health care cuts in recent years, in collaboration with groups such as ACT UP London and Docs Not Cops.
About 20 activists, young and old, sliced a giant NHS cake symbolizing the health service they say is being broken into pieces and sold to private companies.
People wore medical scrubs and masks of people they believe are a threat to the NHS: British business tycoon Richard Branson, Health Secretary Jeremy Hunt and US President Donald Trump.
"Trump has said he wants to raise the price of drugs abroad to put 'America first,' forcing our NHS to pay more for the medicines we depend on," said Iolo Walker, a student who wore a mask of the American president at the birthday party stunt.
The birthday-themed actions are a twist on Prime Minister Theresa May's description last month of the extra £20 billion (US $26 billion) per year the NHS will receive as a 70th "birthday present." They're the latest in a series of protests, small and large, that have taken place across the UK to highlight funding limitations in the lead up to the NHS marking 70 years of service.
The largest event was held Saturday, organized by a collective of groups including the British Medical Association, Unite the Union and the Royal College of Midwives. Buses full of activists, health care workers and patients from across the country gathered on London's Portland Place and marched around 1.7 miles to Downing Street. According to the event's Facebook page, they called for "a publicly owned NHS that is free for all, proper funding and proper staffing, support for our wonderful NHS workers and world class services for every community."
Other protests have also taken place outside of London. In Wigan, Greater Manchester, a strike more than 500 people strong strike took place in May against the August 1 transfer of cleaners, porters and catering workers from the NHS to a subsidiary company. The move is part of the wider cost-cutting trend of outsourcing. Local MP Andy Burnham said in a statement that this should be reconsidered following the government's "new financial settlement for the NHS." Health and social worker trade union Nipsa 730 also protested in Belfast, Northern Ireland on Saturday.
Sean O'Sullivan, head of policy and social care at the Royal College of Midwives told CNN: "We have long campaigned for improvements in resourcing and staffing the NHS and particularly maternity services. This is why we supported the event last weekend.
Read: The UK's National Health Service by the numbers
"There have been improvements with increases in the number of midwives but this increase has not been enough to cope with the rising demands on our maternity services."
O'Sullivan added that while government plans to train an additional 3,000 midwives in England are welcome, it will be another six years before all new trainees will be working in the NHS.
Although May's recent funding announcement has been welcomed by some groups, other activists -- and opposition Labour Party leader Jeremy Corbyn -- claim this will not make up for nearly a decade of austerity measures.
UK spending on health care is just below the average of comparable countries: It spent around 9.7% of its gross domestic product on health care in 2016, less than France (11%) and Germany (11.3%), but more than Ireland (7.8%) and several southern European countries like Italy (8.9%). Meanwhile, the United States spends the most on health care by far, at 17.2%.
For activists like Ray Malone, part of the NHS Anti-Swindle Team, the new injection of funding is of little comfort. "Last year, nearly 70% of new [NHS] contracts went to private companies, most of which don't pay corporation tax," she explained at a screening of a short documentary about the NHS on Tuesday. She pointed out her red flight attendant costume -- a dig at Branson's Virgin Care, which gained £1 billion worth of NHS contracts last year and paid no corporation tax.
For these campaigners, moves toward privatizing health care risk eroding the founding principles of the NHS as "comprehensive, universal and free at the point of delivery."
"It creates a two-tier system. If you've got money, if you're 'first class,' you can have a fast track service to an MRI scan. But if you're 'economy,' then it's back in the queue," Malone finished, mimicking a flight attendant announcement.
Matthew King, a mechanic from east London, attended the NHS Anti-Swindle screening with his partner, Theresa, and son, Raven, who lives with multiple conditions including cerebral palsy, brain damage and quadriplegia due to his premature birth.
In the documentary, King recounted a time when Raven was sick but there were no beds available at their local hospital. The family spent a week on the phone to different specialists trying to get referrals before Raven was finally treated. He lost 2 kilos in that time, and Matthew admits he was worried he would die.
"Without the NHS, our son wouldn't be alive. Roughly every six months he's in for a month of multiple brain surgeries plus many other treatments," King told CNN. "But over the past four years I've noticed less nurses on the wards, longer waits for care -- it used to take 10 or 20 minutes, now you might be waiting hours," he said, adding that he sees government policy on the NHS as the issue -- not the dedicated nurses and doctors who have cared for Raven.
In 2015, researchers linked 30,000 excess deaths to cuts in health and social care. And according to The King's Fund, NHS waiting times have been "deteriorating across the board" with performance standards slipping in recent years.
The four-hour standard for Accident and Emergency rooms has not been met since July 2015 and the 62-day cancer standard for more than three years. The report on waiting times concluded that "Unless additional funding is provided, patients will wait longer to access the urgent and routine clinical care they need."
"Health care is a human right," said Jessica Potter, a lung doctor and public health researcher at Queen Mary University of London.
When asked about what changes she has seen in her time at the NHS, Potter said, "We have more rota gaps than I've ever noticed before, people are under a huge amount of pressure, and when the NHS is understaffed and underfunded in the way it has been by successive governments, then it becomes really difficult to maintain that good relationship with our patients to provide the best care that we possibly can."
The UK population -- including but not limited to activists and health care professionals -- are passionate about the NHS and what it represents.
An Ipsos Mori poll in 2016 found that the health service makes more people proud to be British than their royal family, armed forces or history.
But people are increasingly worried about sustainability of the overstretched service and its ability to provide high-quality care. In February, thousands of non-emergency and routine procedures were canceled to free up beds, but emergency rooms were still overwhelmed with 10s of thousands of people each day.
On the question of whether the NHS is heading for financial crisis, The King's Fund stated that "many large NHS organizations seen as financially stable and effective at managing their resources are now in deficit. Foundation trusts with financial reserves are able to draw on these to deal with deficits in the short term but by definition this is not a sustainable solution to the NHS's funding problems."
British Medical Association junior doctors committee chair Dr. Jeeves Wijesuriya told CNN that they "believe an annual [funding] increase of at least 4% is needed, rather than the 3.4% announced.
"Furthermore, the impact of this funding will depend on how it is spent and priorities. It is crucial that doctors are at the heart of decisions about where the money goes, to ensure it reaches frontline services as quickly as possible."
On Thursday, the BMA officially unveiled "The Long Run," an art installation in collaboration with the British Medical Journal and artists from Goldsmiths, University of London to highlight the good work of the NHS. "The 9-metre long series of marble runs, test tubes, syringes and surgical implements helps us to visualize the amount the NHS spends on supporting us as patients throughout our lives," Wijesuriya said.
More nationwide celebrations have been marked on social media using the hashtag #NHS70. But the anniversary is bittersweet for many -- while some see a legacy to be celebrated, others see the possible challenges going forward, and feel it's a day of mourning.