Scotland leaving the UK would be a major disruptive change for our country.

Few would deny this. Indeed, for nationalists it is precisely this disruptive change that makes separation so alluring.

Yet history shows us that, following large-scale upheaval, there's one group in society left paying the bill and it's the one that can least afford it.

As the big issues in the referendum debate emerge, it is clear that the working and lower middle class people of Scotland will pay the price for the SNP's obsession with independence.

Already in my life time there have been three major disruptive shocks that have affected the UK.

First, there was the oil shock of the 1970s, which saw oil prices quadruple in the four months from October 1973.

Secondly, the industrial shock of the 1980s; people forget that Scotland elected 22 Conservative MPs in the 1979 General Election but even those attracted to the disruptive effects of the Thatcher revolution couldn't have foreseen the full impact of those 11 years.

The third was the financial shock. The 2008 global financial crash during which, if it hadn't been for the broader shoulders of the bigger UK, the Scottish banks could have been wiped out.

There are some important differences between independence and these past shocks. The first is that this is a Scottish decision with international impacts rather than an international event with Scottish consequences. It would probably be the first 100%, "Made in Scotland" disruptive change of my life.

The second major difference is that a vote to leave the UK is irreversible. The other events I've mentioned were prolonged but not permanent. If we vote for independence in September there is no going back. We will have bought a one-way ticket to a deeply uncertain destination.

Despite these differences, there is one common thread linking the disruptive events of the past with potential separation from the UK: those in the working and lower middle classes will pay the price for longest.

The oil crises of the 1970's pushed inflation up to almost 25%, hammering working people already struggling. In the early 1980s, 10% of Scots lost their jobs. My family had its own response. We emigrated.

In the wake of the 2008 global financial crisis, working families have again paid the price; in recent years Scotland has seen real wages fall by nearly £1300.

With independence it is clear that there would be large increases in the cost of living for hard-working Scottish families.

The expert evidence tells us that interest rates would be higher. We would be a new state borrowing on international markets. Even before you take into account any effect on interest rates of, for example, setting up a new currency to replace the loss of the pound, economists have suggested that interest rates would increase by 1% or 2%, and perhaps more.

The latest annual debt statistics from the Money Charity revealed that the household average debt was £6000. A 2% increase in interest rates would cost a lower-paid working family another £120 they can ill-afford. Think of a family that's just taken out a typical mortgage of £80,000. Every extra 1% on interest rates is £800 out of the household budget. A 2% rise means somehow finding an extra £1600.

These families are already spending nearly 20% of their income on housing costs. Even an extra 1% on the mortgage would be too big a risk.

Higher interest rates in an independent Scotland would mean that many Scottish families would be £1000 worse off.

This inconvenient truth isn't something the nationalists will tell families. The SNP are too worried about trying to make history to pay enough attention to the Scots who are trying to make ends meet.

The reality is that hard-working Scottish families would be the ones who pay the price of the SNP achieving their dreams.