Hundreds of junior doctors have marched on central London to vent their frustration amid a bitter pay row at the start of a four-day strike.

Protesting medics chanted “Claps don’t pay the bills” and blew vuvuzelas as they made their way from Trafalgar Square past Downing Street and the houses of parliament.

Protesters also chanted “We are off to Australia”, in reference to higher wages paid for junior doctors abroad.

It comes as NHS bosses warn the strike action – which began at 7am and will continue until Saturday morning – will cause “unparalleled” upheaval and will be the “most disruptive in NHS history”.

The strikers were holding signs reading “Is it any wonder we’re going under” and “No wonder Dr Watson turned to crime fighting”.

Tourist buses and lorries beeped their horns in solidarity with the protesters. The doctors stopped to give bus drivers a cheer as they beeped their horns.

An estimated 250,000 appointments, including operations, will be cancelled as around 50,000 junior doctors in England are taking part in the industrial action.

The government and the British Medical Association are deadlocked over junior doctors demanding a 35% pay rise, which the union argues will bring wages to 2008 levels.

A Downing Street spokesperson said the 35% demand is “completely out of step with pay settlements in other parts of the public sector” and would cost £2 billion.

Medics on the picket lines have spoken about “living on the breadline” amid difficult working conditions.

Trainee anaesthetist Ada Zembrzycka said her colleagues are using food banks as they struggle with the cost of living.

The 27-year-old, who works at Whipps Cross Hospital in east London, said: “If the pay cuts continue I will not only struggle to pay (for) my exams but for groceries and my Tube tickets.

“Rent is increasingly going up and I can’t keep up.”

Speaking on a picket line outside St Thomas’ Hospital in central London, she told the PA news agency: “I do have colleagues who have to borrow money from their families to pay rent this year.”

Dr Hugh Adler, 35, a senior registrar in infectious diseases who was on the picket line outside the Royal Liverpool University Hospital, said: “The headline reason we’re here today is pay erosion.

“People feel devalued, they’re struggling to make ends meet. People are choosing to leave the NHS and we’re seeing the gaps in the rota.

“We want to stop this exodus and haemorrhaging of staff, particularly junior staff who are paid £14 an hour after coming out of a six-year degree.

“They could go to Australia and work fewer hours for more money.”