Scottish Labour's health spokesman Anas Sarwar said: "This is an uncosted announcement with a "Brexit dividend" promise plucked straight from the magic money tree, and even then it falls short of what the health service needs to stand still". The announcement follows 11th-hour discussions between Downing Street, Hammond, Hunt and Simon Stevens, the chief executive of NHS England, over the figures.
He also insisted the government was able to announce the funding injection not only due to the "Brexit dividend", but also a "deficit reduction dividend" and a "jobs dividend".
Senior research economist at the Institute for Fiscal Studies, George Stoye, said that the 20-billion-pound boost is just enough for the system to stand still, without taking into account any new pressures.
The prime minister said this will be partly funded by a "Brexit dividend" - money Britain will supposedly save from no longer contributing to the European Union's budget.
In what is her biggest and boldest policy announcement since her election disaster past year, the PM announced the extra money for the NHS to mark its 70th birthday.
Historically, every year since the NHS was created, the amount of money it receives over the top of inflation has increased by 3.7%.
Proposals under consideration for funding the pledge alongside the Brexit dividend are believed to include freezing the thresholds for the personal allowance, the rate at which people start paying income tax, and for the 40p rate from April 2020.
Mr Hunt said: "This long-term plan and historic funding boost is a fitting birthday present for our most loved institution". That bit would need to reach an additional 1,200 to 2,000 pounds per household a year by 2033 to 2034, according to the IFS.
He added: "These will still be tough years ahead".
The Scottish government will receive a £2bn boost as a result of United Kingdom government investment in the NHS, the Scottish Conservatives have said.
Answering questions afterwards the prime minister said greater tax revenues would be part of the answer. The International Longevity Centre calculated that if things carry on as they are, health spending could rise from around 6 percent of GDP in 2019-20 to 16.4 percent by 2064-65, which would be completely unsustainable. "Tackling the huge disparity in access to mental health care will have to be an aspiration, rather than reality for another five years".
In media interviews, May said her finance minister would set out plans before a government spending review expected next year.
Asked whether he was ready to defeat the government, he replied: "The group is quite determined that the meaningful vote pledge that was given to us has got to be fulfilled - I think that is abundantly clear".
Scottish Secretary David Mundell has also called for the funding to be passed on to NHS Scotland, saying the money "has the potential to make a real difference for people in Scotland".
"We have looked carefully at what we have put into the NHS to ensure that we deliver world-class healthcare".