This is a copy of an article I wrote for MediaTel, published yesterday.

Total media spend by supermarkets during January this year was down a substantial £6 million year on year, from £33.2 million in January 2011 - a fall of nearly one fifth.

Press was the biggest loser, which saw a massive fall of £3.9 million. TV spend fell £1.9 million and Direct Mail £1.2 million. There were two big winners though. Radio and online spend each increased dramatically, by 91% and 40% respectively.

Although these changes may be a blip (which I doubt), it is more likely that this indicates a shift in media strategies by at least some of the supermarkets toward more careful targeting.

The drive to look at supermarket media expenditure originated from research released today by Starcom MediaVest Group, which looks at supermarket loyalty nationally and regionally. Using TGI data, it shows that 8.75 million supermarket shoppers in England and Wales lack loyalty towards any of the big six supermarkets at which they shop. This represents 20% of the nations' 45 million regular supermarket shoppers.

In particular, it shows that Waitrose has the least loyal customer base, with 23% of its two million regular customers classed as 'Swapper Shoppers' - who are likely to shop with a rival. At a regional level, Waitrose faces its biggest challenge in London and the South East, where its customer propensity to switch supermarkets is especially high.

It is no coincidence then that out of all the supermarkets, Waitrose shifted its media spend the greatest during January. It makes sense for a supermarket that centres on a particular region to increase its Door Drop spend, which Waitrose did by 150%.

What makes less sense is that unlike most of the other supermarkets, Waitrose dropped its online spend by a massive 92% after having enjoyed such a good Christmas. This is also especially surprising because when deployed intelligently, online media can be used to carefully target down to regional and even city level, and create ongoing interactions with people. Both are things that would benefit the supermarket hugely, given its under pressure in London and the South East from 'Swapper Shoppers'.

Waitrose is also swimming against the tide when it comes to online media spend. Most of the other supermarkets are taking advantage of this precision targeting and conversation creation, having increased their online media spend in January. This rise was led most impressively by Tesco. The UK's biggest supermarket spent a fifth of its media budget online and increased its spend by nearly 60%. Marks and Spencer and Asda each joined Tesco in dramatically increasing their internet spend.

The Regional Shopper Risk Index forms the third wave of research in Starcom MediaVest Group's #SupermarketUK retail study. The study shows 8.75m supermarket shoppers in England and Wales lack loyalty towards any of the big six supermarkets. Of the 45m regular supermarket shoppers, nearly 20% of these are promiscuous ‘Swapper-Shoppers’ who show no allegiance to Asda, Co-op, Morrisons, Sainsbury’s, Tesco or Waitrose.

SMG analysed Kantar’s TGI data to identify 'Swapper Shopper' behaviour in 21.1 million regular shoppers across England and Wales revealing regional variations. Waitrose has the least loyal customer base with 22.6% of its 2.03m regular customers classed as 'Swapper Shoppers' who are likely to shop with a rival. In real terms Tesco is most at risk of turncoats due its dominant market share with 3.51m ‘Swapper Shoppers’, the study has revealed.

Proportionately five of the big six have around a fifth of their regular shopper base at risk with Co-op and Morrisons shoppers marginally less likely to switch allegiance than Asda, Sainsbury’s and Tesco. “The study is particularly interesting as it shows a large proportion of each supermarket’s shopper base is vulnerable. Supermarkets need to be aware of this and constantly work towards keeping their customers satisfied, paying special attention to high risk areas” said Thaer Namruti, Analytics Director, Starcom MediaVest Group.

At a regional level, Waitrose faces its biggest challenge in London and the South East where its customer propensity to switch supermarkets is especially high. Co-op’s base of shoppers in Wales and the South West are the second group most at risk of switching supermarket preference.

The Regular Shopper Risk Index also exposed differences by average weekly spend levels (table below). Waitrose and Sainsbury's power base of London and South East is consistently at risk across all spend levels. This high risk correlates with store network reach that attracts a larger proportion of customers and represents a greater number to defend from the competition. Both have an equally loyal base in the North, with this loyalty for Sainsbury’s extending across Wales and the West.

The Co-op's highest risk customers in Wales and the South West are light spenders and so moving these up the value chain to medium spenders carries significant risk. Asda followed by Tesco has the lowest risk shoppers across the board based on spend levels and so the greatest opportunity to increase shopper expenditure.

“The Regular Shopper Risk Index shows that nearly 9 million of us are ‘Swapper Shoppers’ with little loyalty to any of the big six supermarkets, rather like a ‘swing voter’ in political terms,” said Stewart Easterbrook, CEO, Starcom MediaVest Group. “Waitrose has the highest proportion of potential defectors possibly due to increased sensitivity of their customers in a tough economic climate coupled with a high concentration of stores in the South East and London facing considerable competition. Tesco too has cause for concern with the greatest market share, the largest amount of promiscuous shoppers and so the most to defend. As the UK supermarket wars hot up, this study highlights the national and regional battlegrounds that the big six need to win to keep their tills ringing.”