Smoke and mirrors, damn lies and statistics - this is the reality of the education sector today.

Here is what chancellor George Osborne said in his March Budget speech: “We are taking difficult decisions now so we can reduce the deficit and protect our NHS and schools.” Here’s what the former education secretary Michael Gove said last December: “The underlying schools budget will be kept at flat cash-per-pupil for 2014-15.”

So you’d be forgiven for thinking that this year’s school budgets would look pretty similar to what has gone before. The reality is rather different.

Our school has more pupils than last year. On a pound;7 million budget, our income is down by pound;216,000. That includes a reduction in the sum we get for each pupil, a reduction of funding based on special educational needs and low prior attainment, and lowered sixth-form funding. It is an overall cut of 2 per cent.

But this isn’t the full story. The government has very kindly given both teaching and support staff a pay rise of 1 per cent, and incremental rises or performance pay have added pound;122,000 to our wage bill. This means that we have to find savings of pound;338,000. Then add the hidden cost of inflation. Result: the politicians’ “protected” schools budget is, in reality, a cut of 5 per cent for us this year.

Any teacher under the age of 40 has a rude awakening ahead. They have only worked in schools since the Blair government turned on the cash tap in 1997.

When I first became a head of department in the early 1990s, we used our bookstore as an office. I salvaged an old swivel chair my father-in-law was throwing out and pleaded with the bursar for a few square metres of carpet. There were no teaching assistants. ICT meant a couple of stand-alone BBC Micros. We reproduced worksheets using a spirit-based Banda machine. Each teacher received one blue and one red biro for marking per term. We were that lucky.

Teachers have since grown used to being treated like professionals. Salaries and working conditions have improved and whatever resources they have requested - books, computers, professional development, off-site visits - have been forthcoming.

What saddens me most about the impending cuts is the inevitable impact on our most vulnerable pupils. Rising budgets have enabled us to support those who would hitherto have been lost in the system. We have made personalised education a reality with teaching assistants, smaller class sizes and other resources. We have supported those at risk with counsellors. Schools are now a better place to be for those with additional needs.

We have been expecting cuts since the crash of 2008, but despite the rhetoric of austerity, we have so far largely been spared. That changes from next month, and it would easier to bear if the politicians were honest about the impact. With a 2.4 per cent rise in employers’ contributions to pensions due in 2015, the stealth cuts are only just beginning. If your father-in-law is throwing out any chairs, I’d bag them now.

Roger Pope is principal of Kingsbridge Community College in Devon