DEREK Mackay is a lot more fun than he let on as he delivered his first budget.

Quick witted and a popular turn at SNP conference, he nevertheless did his utmost to disguise his character and drone away for 20 minutes, sounding eerily like a Tannoy in a bucket.

Chancellors and finance secretaries often play the role of a dull but reassuring bank manager.

Mr Mackay’s performance partly belonged to this long tradition, but also had a strategic side.

The SNP leadership is keenly aware that 2016 has been a disconcerting year for voters.

The shock of Brexit was followed by Donald Trump’s election as US President.

It is therefore eager to be seen as a steady administration in a turbulent world.

At Westminster, the first budget in a parliamentary term is often the moment of maximum pain, when Chancellors hike taxes and cut spending in ways they hope will later be forgotten.

Instead of following that template, the SNP plan was for a deliberately predictable budget.

It was the last leg of a three-part process that began with the policies in the election manifesto.

These were then given legislative heft in September’s programme for government.

The budget was meant to complete the picture by showing where the money goes.

So, as promised in the spring, the threshold for the 40p income tax rate was raised by inflation, making it more expensive for upper earners in Scotland than in England, but not by much.

There was a £60m down payment on the plan to double free childcare.

More small businesses were helped with their rates.

The notable wrinkle was the abandoning of a manifesto pledge to raise £100m for schools by plundering the money from higher council tax rates.

This was dropped as unworkable after councils rebelled, but Mr Mackay overcame it with a small flourish by saying he would find £120m for schools to close the attainment gap instead.

There was also a post-budget row between councils and the government over how much funding would be going to authorities next year: ministers said up to £240m more than in 2016-17, while councils said £350m less, if you focused on discretionary spending pots.

The arguments will continue into the New Year, as the SNP tries to find another party - most probably the Greens or LibDems - to support it at the key Budget Bill vote in February.

But overall, as the Fraser of Allander Institute put it yesterday, the budget “contained little in the way of new surprises beyond what had been widely trailed in advance”.

The Chartered Institute of taxation in Scotland called it a “safety first” budget, which showed “only the most tentative signs of divergence between Scotland and the rest of the UK”.

In other words, just the sort of drowsy summaries the government was hoping for.

And yet… Mr Mackay couldn’t drain all the excitement from his announcement.

It was a truly historic budget for Holyrood, thanks to new devolved tax and welfare powers.

While that £300 tweak in income tax isn’t radical in scale, it does represent a radical moment fin devolution - the first time since 1999 that income tax rates will differ across the border.

Despite himself, Mr Mackay has started a ball rolling which could go a very long way.