The battle to win the hearts and minds of Britain’s grocery shoppers is heating up.

The major multiples have significantly ramped up their advertising spend year-on-year. Of the big four, Sainsbury’s has increased its investment the most, spending £5.75m last month – almost double what it spent last September. As the credit crunch really starts to hit consumer spending, they’re all trying to reinforce their value-for-money credentials and fend off the threat of the hard discounters.

A year is a long time in advertising land – last September, Sainsbury’s key focus, both in its TV and press campaigns, was on organic. Now, it is firmly on the growing number of budget-conscious family shoppers.

As well as the ad in which Jamie Oliver whips up a Freedom Food chicken meal in-store with the help of an adoring member of staff (see picture), Sainsbury’s is running an ad featuring a more down-to-earth, common-or-garden working mum ‘feeding her family for a fiver’.

Since the campaign broke on 3 September, the supermarket has invested £2.3m on TV advertising across both terrestrial and multi-channel stations. Over the four weeks, 84% of housewives with children will have seen Sainsbury’s campaign an average of seven times each. If each of these housewives were to spend the Sainsbury’s fiver, the supermarket would net £28m. Its aim is to lock in existing shoppers and attract a bigger slice of those housewives not loyal to a rival’s store. The latest burst also underscores a shift in media focus for Sainsbury’s. In the year to August, it had spent two thirds of its TV/press budget on the box but last month this rose to more than 80%.

Tesco – aka ‘Britain’s biggest discounter’ – is also pushing the value message. A price-focused strategy has even been adopted by M&S and Waitrose. Out went Dervla Kirwan’s seductive tones promoting its luxury foods, in came £10 Dine In for Two. This month Waitrose was back on TV with three different treatments including a ‘dinner for two, dessert and wine for £10’ message.

Somerfield has increased its ad spend considerably too, running many 10-second commercials promoting specific offers.