In marking their anniversaries this week with TV ads and eye-catching in-store activities, both Sainsbury's and Marks & Spencer are no doubt hoping a trip down memory lane will fire the imagination of shoppers, and translate into increased sales.

Sainsbury's TV ad is 60 seconds of sepia and has more than a passing resemblance to the Hovis epic of last autumn. The journey through time begins in 1869 with a young urchin dipping a soldier in a boiled egg to demonstrate "good food affordable for all", before charting some of the landmarks in its 140-year history, such as its early employment of women in 1914, the introduction of avocados in 1962 (a claim that M&S also makes), and the brief appearance of trendy Anya Hindmarsh reusable shopping bags in 2007. Sainsbury's will also be serving cake in its stores this weekend. Not to be outdone, and celebrating 125 years, M&S held a three-day penny bazaar across 300 stores this week - tying the retailer to its historic roots as a discounter - selling everything from tea towels and mugs to fruit jellies and drinks for just 1p. It's also launched a new range of clothing and food items inspired by old bestsellers.

The bazaar was opened by model Twiggy at the company's flagship Oxford Street store. She also fronts an ad campaign, which also takes the viewer through significant moments in its history, featuring Michael Marks's market stall in Leeds in the 1880s and the first ready-made prawn curry, which "liberated housewives" in the 1970s, claims Twiggy.

Such lavish campaigns don't come cheap. The ads and in-store activity are equivalent to running a Christmas campaign, with between £5m and £6m spent on advertising and an additional £2m funding the penny market promotion, according to M&S marketing director Steven Sharp.

So CEO Sir Stuart Rose will be pleased that, amid the doom and gloom surrounding Tuesday's announcement of a 39.9% slump in full-year pre-tax profits, queues for the Wednesday rollout were forming at some stores as early

as 5am, and by midday M&S had

reportedly served 900,000 people - three times its usual number for that time of the week.

Sainsbury's will be hoping for similar success this weekend. But with the two birthdays clashing, there's a palpable edginess. Customer director Gwyn Burr is dismissive of M&S's penny bazaar. "A lot of people may have been disappointed," she says. "We sell two million items every two hours. We are about substance. I'm not sure customers want stunts."

As well as the cake cutting, Sainsbury's is using the anniversary to introduce a new initiative - Local Charity of the Year - where customers choose a charity to benefit from each store's fundraising. "It's reinforcing what Sainsbury's has meant to communities through the years," says Burr .

Both retailers are attempting to convey a message of heritage and tradition, but they are also trying to show they can innovate as well, says founder Jonathan Gabay. "Everyone in marketing and advertising will know that people always yearn for the past. It has always worked. But you've got to be cautious in 2009, because we are incredibly marketing savvy now," he warns.

So will anyone win this battle of the birthdays? Gabay believes both campaigns will be successful because the retailers are conveying quality as much as nostalgia.

Some question whether the respective anniversaries are big enough to warrant celebrating. "I keep being asked about this, but Hovis did 122 years and that's a very strange anniversary," says Burr. "We had this in the calendar three or four years ago. I think it would wear a bit thin if we weren't doing so well at the moment."

In the meantime, Sir Stuart will be hoping that, on the contrary, the eye-catching penny bazaar stunt will be the catalyst for a similar recovery.