ON returning from two weeks' game watching in the splendid and genuinely unique Okavango Delta in Botswana where I lived over 30 years ago, I have found there are all the superficial signs of a marked improvement in the prospects for both the UK and Scottish economies.

A strong recovery seems - at long last - to be under way.

Regular readers of this column will know that I have been sceptical so far as at least the sustainability of this recovery is concerned. And that remains the case.

We are certainly not back to the "old normal" of the Blair/Brown boom years and we may yet face troubles in turning an essentially consumer-led growth path to one founded upon enhanced competitiveness, strong investment and encouraging exports.

The worry is not so much about the next 18 months or so up to the next UK general election as the medium term. Could this recovery end in more tears?

The first official estimate suggests that UK GDP growth in the third quarter of 2013 (July through September) was 0.8%. This was a marginal improvement on the latest estimate for Q2 - 0.7% - and substantially higher than the average since the recession of 0.2%-0.3%.

The Monetary Policy Committee has deemed this a "robust recovery", but a little examination of such detail as is available for Q3 justifies pause for thought.

It looks as if the prime driver of this accelerated growth is the consumer. Well, to some extent this is good news as the consumer accounts for markedly the largest part of our economy, and rising consumer confidence is most welcome. However, this rapid growth in consumer spending comes while real wages continue to fall and unemployment risks abound. Retail spending in Q3 grew by a massive 1.5%, the fastest growth recorded since the 2008 recession.

But with real wages falling how is this being funded? My friends from Fathom have calculated that a major source of such dynamism is unsecured credit - doubtless from various sources including credit cards and payday lenders.

Unsecured credit is growing faster than household income. Overall that means that net savings are declining and net indebtedness is again on the rise.

Clearly not everyone has increased their debt. Some people will continue to focus on boosting their savings to diminish indebtedness and return to more sustainable levels. They will be relating their debts and debt repayments to their wealth and incomes. Others may be being less careful - less prudent.

For some, especially in the South of the UK, this may be related to the improving story in the housing market. With house prices stabilised and now rising, not least thanks to UK Government interventions, increased perceived wealth may be one factor fuelling consumer spending.

I simply do not see how the way out of our problems can lie in once more driving up credit and consumption. Household debt is already far too high to be sustainable. It has to decline relative to wealth and incomes, not rise.

Scotland's savings ratio is higher than the UK's, but we are also experiencing a trend of rising borrowing. We are not immune from this worrying trend.

Of course the recovery to date has still not taken us back to the pre-recession peak. A straightforward calculation shows UK GDP 2.5% below that peak, albeit 5% above the previous floor reached in 2009.

I am indebted to Brian Ashcroft of the Fraser Institute for a more sophisticated view of how Scotland compares in this context to the UK. On the straightforward basis, Scotland has recovered slightly further from the trough than the UK as a whole. But, as Brian has pointed out, this story is distorted by oil and gas. Data for this sector are in the UK data, but not those for Scotland. Offshore is treated as a separate region. Oil and gas output has declined sharply, and if these data are excluded from the UK calculation, then the UK performance in recovering from the trough is much stronger than in Scotland. (Adding the oil and gas data into Scotland would accentuate this differential.)

Brian has also echoed a theme from this column: "Unless net exports and investment recover soon we have doubts whether the recovery can be sustained."

One hopeful sign on this front from the latest FAI report is that Scotland's labour productivity has improved relative to the UK. This may be a case of "damning with faint praise" as the UK productivity performance is suitable for a horror story.

Something happened as a result of the banking-sector-related recession starting in 2008 that has adversely affected productivity trends. UK productivity remains 5% below its pre-recession peak and has declined far more compared to the USA and other competitors.

To achieve sustainable recovery we need to be competitive and export more. To be competitive we need more business investment (no sign of that yet) and rising labour productivity. That is the same for the UK and Scotland. Despite 2013's more positive GDP data there are no really positive signs as yet on exports, investment or labour productivity. Sad but true.

Jeremy Peat is director of The David Hume Institute