Having just returned from two weeks under the Kalahari sun in Botswana - where I lived and worked 35 years ago - I would much prefer to report on developments there rather than events back in icy and general election- besotted Scotland.

I shall (largely) resist that temptation but do wish to pick up a couple of points from that remote diamond-rich small nation which appear of relevance back home.

First, demand for diamonds is muted. Botswana is just about the most efficient, and perhaps the largest, global source of this luxury product. However, output is being artificially constrained while demand remains well below pre-recession levels. The focus of demand now is on China - where else - and the muted demand is just another sign of the sharp deceleration in that economy and the risks that this brings globally.

Second, while staying in the capital city, Gaborone, data emerged showing that inflation has fallen to a post-independence low of around 2%. In the context of Botswana and Africa more generally this is a remarkable development. The Bank of Botswana is, inevitably, re-visiting monetary policy and deflation concerns are emerging.

In other words, the twin risks of deceleration in the global economy and deflation are evident even at the edge of the Kalahari Desert! That was most unexpected.

On arriving home I found that the Bank of England has now asked the major UK banks to 'stress test' themselves against a scenario in which global (including China) growth decelerates further at pace while deflation becomes embedded. This requirement from the Bank has to make sense, even in the midst of an election campaign. This is just the type of 'risk scenario' - note not yet a central expectation - against which banks should test sensitivities and see how they could adapt and adjust without facing the type of trauma suffered in 2008.

Meantime the (relatively) good economic news keeps on coming through. Growth of UK GDP for 2014 has been revised up to 2.8%, the highest level since way back in 2006. At the 2015 Budget the Office for Budget Responsibility (OBR) edged up its growth forecasts to 2.5% for this year (from 2.4%) and to 2.3% next year (from 2.2%). These are encouraging pieces of data, but I still find it difficult to be wholly positive about achievement or outlook.

So far as achievement is concerned do note that GDP per head, to me more important as a measure of affluence and economic wellbeing than GDP per se, remains 1.2% lower than it was pre-recession. On average each member of the population is marginally worse off than seven years back. These figures come from the Office for National Statistics (ONS), which also produces estimates of 'net national disposable income', the income actually available to UK residents. This is more than 5% below pre-recession levels and has not really picked up at all over the past three years.

So all the positive news - jobs up, unemployment down, GDP up, inflation down, etc. - has to be tempered by caveats. Are the jobs full time or part time; do zero hours contracts count as good news? Will higher GDP alongside lower GDP per head mean 'feel good' or 'feel uncertain'? Will low/negative inflation boost living standards and hence consumption, or lead to expectations of more price falls to come and hence, amidst uncertainties, lead to deferred consumption raising the deflation risk to a higher plane?

Further, turning to the outlook, lurking behind the GDP data are continuing causes for concern regarding sustainability. Growth remains unbalanced, with business investment still too low for comfort and productivity, specifically the lack of significant productivity growth in the UK over the period since the recession, a major worry. The data suggest that output per hour worked in the UK declined in Q4 2014 and remains lower than in 2007. The ONS stated that 'The absence of productivity growth in the 7 years since 2007 is unprecedented in the post-war period'. That is not the case globally, or even in the EU. Indeed I saw one estimate that the French work force could take a holiday each Friday and still produce the same amount per head as their UK counterparts.

The OBR remains in the optimists' camp and sees productivity growth rising to 2.5% per annum by 2017. Let us hope that they are correct, but this will be dependent upon a significant pick up in business investment - which fell back in the last quarter of last year and remains remarkably subdued - and a boost in high skilled and high output jobs.

If business investment and hence productivity do not improve, then the UK will remain dependent upon the consumer. That takes us back to 'the feel good factor', expectations for wage growth and the impact of low or negative inflation. Given 'feel good' and wage growth the outcome of low inflation could be strong consumer demand. If households are less positive, then any boost to net incomes from low oil prices and negative inflation could lead to higher savings rather than higher expenditure; and hence a return to sluggish growth.

The latest Scottish Government economic strategy lays great emphasis on higher productivity. That has to be the correct ambition. But how is this to be achieved? Nobody really knows, so how about a 'Productivity Commission' to investigate how to boost productivity growth alongside business investment and optimal use of our skilled labour force?

Jeremy Peat is visiting professor at the University of Strathclyde International Public Policy Institute