It was a rare hit for a leader who struggled so badly to engage with the public, a pithy soundbite with a clear message: Of course she would like to give public sector workers a pay rise, but the money was not there. Or at least not without extra taxes or cuts elsewhere. Money doesn't grow on trees.
Three-and-a-half years on, the landscape has changed beyond recognition. Not only has the 'strong and stable' Mrs May made way for Boris Johnson, whose leadership pitch was based on promises of extra public spending, but coronavirus pandemic has seen normal rules about fiscal responsibility go out of the window.
Since the start of the pandemic, the Government has spent £46.4 billion on furlough payments alone. Another £12 billion has gone on coronavirus vaccines, even the Eat Out to Help Out scheme, offering cut-price meals over the summer, cost the Exchequer £849 million.
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So where has all this money come from, given that the country was so strapped for cash three years ago?
The short answer is certainly not the magic money tree. And anybody thinking this is going to come without pain is going to be in for a rude awakening, warns Ian Jackson, a senior economics lecturer at Wolverhampton University.
While the coronavirus vaccine may give hope that the pandemic could soon be over in this country, the economic troubles are only just beginning.
The figures are truly eye-watering. The UK Government borrowed £34.1 billion last month, almost six times what it was for the same month last year. Public sector debt running at 99.4 per cent of national income, the worst ratio since 1962.
"In scale it's comparable to the Great Depression," says Jackson.
"My feeling is it's going to be 20-25 years before we start to get back to normal."
And with figures like this, anybody who thinks the past decade has been a period of austerity is in for a big surprise.
For all the stern talk, the reality is that public spending has increased steadily over the past 30 years. In 1991, it stood at £139 billion, and had more than doubled to £380 billion by the time of the credit crunch in 2008. And since then it has continued to rise every year bar one, to £520 billion in 2019.
But the coronavirus has blown these figures out of the water. By the end of the 2020/21 financial year, government spending is expected to reach £928 billion, almost 2.5 times the figure at the beginning of the financial crisis.
Of course, this is in no small part down to the amount of support the Government has provided for individuals and businesses during the pandemic. Day-to-day spending is up by £169.3 billion, or 30.7 per cent, in the nine months up until December. But while public spending has rocketed, tax receipts fell by £39.6 billion over the same period, a drop of 7.8 per cent compared with the same period in 2019. Unsurprisingly then, the national debt has also risen: it is projected to reach £393.5 billion by the end of March, 2.5 times the £158 billion at the height of the financial crisis in 2009/10.
But while these figures are unquestionably huge, they probably mean little to the average person more concerned with paying the bills and keeping up with the mortgage or rent. And some will ask why is this a problem? With interest rates at record lows, doesn't it make sense to borrow a bit more money until thing get better?
Similar arguments were used in the wake of the 2008 financial crisis.
"The arguments against austerity were that George Osborne was treating the economy like a household budget, when you could pass some of the debt onto future generations," says Ian Jackson.
"But when we're expecting our children and grandchildren to be paying for a debt of this size, we can expect them not to be too happy about it."
The other problem is that deferring debt indefinitely can be a very risky business, particularly if the financial markets lose confidence in the Government's ability to pay. Students of economic history will recall the events of 1976, when the money effectively ran out, forcing then-chancellor Denis Healey to secure an emergency loan from the International Monetary Fund. Aside from the national humiliation of a developed country having to seek aid from the IMF, the terms imposed on the loan left the Government hamstrung in what it could do in terms of economic policy.
That year, then prime minister Jim Callaghan was met with stony silence when he addressed the Labour Party conference with the grim warning: “We used to think you could spend your way out of a recession and increase employment by cutting taxes and boosting government spending. I tell you in all candour, that option no longer exists.” His words were not well received by party members, but in truth he was merely stating the obvious. You can only borrow money if you have the means to pay it back. The recent troubles facing the Greek economy reinforce that.
Ian Jackson does not think Britain is at that stage yet, mainly because unlike in the mid-1970s, the UK still enjoys the confidence of the lending markets. But failure to address the debt crisis could lead to the picture changing very quickly.
"I don't think we are quite at that stage, the ratings agencies like Standard & Poor are keeping on side with the British Government, they think we are a good risk," he says.
"The issue will be if they start to get jittery about the ability of the UK to pay it back. If we were then hit with a rise in interest rates, that is when we would start to be in trouble."
In this respect, the UK has the advantage that the rest of western Europe is in the same boat. While Britain's debt, at 99.2 per cent of GDP sounds astronomical, it is mid-ranking compared to our neighbours: worse than Sweden, Netherlands, Ireland and Germany, but not as bad as Spain, France, Italy and Greece, which tops the charts at a mind-boggling 200 per cent of national income. If the money markets get nervous, it will probably be these countries that struggle first.
For most people, a more tangible economic impact of the pandemic will be the effect it has on unemployment.
The highest UK unemployment rate in living memory came with the Great Depression, when it breached the 20 per cent barrier, although in some of the worst-hit areas, mainly in the north of England, the figure reached 70 per cent. More recently, postwar unemployment peaked at 11.9 per cent in 1984.
The one thing in the UK's favour this time around is that it started the pandemic from a pretty strong position, with a record number of people in work, and unemployment at just 1.36 million or four per cent of the labour force. Latest figures released this week showed unemployment had risen to five per cent, its highest level since 2016, but still better than many had been expecting, and well below the EU average of 7.5 per cent. Julian Jessop, one of the more bullish commentators, forecasts that unemployment will peak at below six per cent – just over two million – this year, before beginning a rapid rebound.
Ian Jackson is more cautious, pointing out that there is usually a time lag before an economic contraction makes itself felt in unemployment figures.
"I personally think the Government has done a really good job with the furlough scheme in protecting jobs, but the problem will be when that comes to an end," he says.
"I think we will see unemployment climbing to seven or eight per cent, it will double."