It was the furore last month following stories that Lord Sainsbury had donated pounds 1m to the Labour Party which confirmed the supermarket chiefs as the all-powerful industrial barons of our time.
Until then they had managed to hide behind their vast corporate public relations budgets to project an image of caring service providers or extended family grocers.
But the donation gave rise to speculation as to just how much influence the supermarkets could generate with their enormous collective wealth.
The big four supermarkets (Tesco, Sainsbury, Asda and Safeway) have a combined annual turnover of over pounds 40bn and make pre-tax profits of pounds 2.1bn. Lord Sainsbury's private family wealth is estimated at pounds 2.5bn.
The news of the Sainsbury chairman's political patronage immediately prompted questions about a possible hidden agenda. The supermarkets, it was observed, had been experiencing rebuttals from planning authorities over their proposals to build out-of-town superstores.
Prior to the election, Lord Sainsbury and senior representatives from Tesco and Safeway had met Tony Blair to complain about the tough new planning guidelines on out-of-town stores, imposed by the then Secretary of State for the Environment, John Gummer.
Since the election, Lord Sainsbury has been made a Labour peer and Sainsbury's has been given the go-ahead for a large-scale project at Richmond upon Thames which had run into local opposition.
Mr Blair said that to link the Richmond decision to the donation was "rubbish" and "ridiculous". Nevertheless, the row ensured that the public now saw supermarket chiefs as political animals as well as the people who sold them nice things and made their lives easier.
It was not, in fact, Lord Sainsbury's first foray into political patronage. In the 1980s, he had helped to finance the Social Democratic Party.
Other supermarket giants have strong links to the Conservative Party, under whose government they grew into the corporate giants they are today.
Archie Norman, chairman of Asda, is now Tory MP for Tunbridge Wells, and the company retains Lowe Bell, the public relations firm established by Baroness Thatcher's close adviser Tim Bell, for promotion and lobbying.
Safeway, under its previous name, Argyll Group, made a one-off donation of pounds 30,000 to the Tories in 1992-93. Tesco was also linked to the Tories through former Westminster Council leader Dame Shirley Porter, daughter of the Tesco founder, Sir Jack Cohen.
In the arts, various branches of the Sainsbury family privately support the Sainsbury Wing at the National Gallery and the Sainsbury Centre for visual arts at the University of East Anglia. As a company, Sainsbury's sponsors community-based projects as part of its Arts for All scheme, mainly aimed at encouraging participation in theatre, music, ballet and opera.
Supermarkets are also increasingly looking to promote themselves by providing money for schools. Sainsbury's runs a Schoolbags voucher scheme, in which 17,000 schools took part last year. Vouchers, issued for every pounds 10 spent in the store, can be exchanged for school equipment. Tesco has a Computers for Schools scheme, offering vouchers for every pounds 25 spent in-store. The company says 11,000 schools took part in the scheme over the last year, claiming computer equipment worth pounds 5m.
Asda set up the Asda Foundation over five years ago, with the promise to double any money raised by its stores for local charities. Last year the company raised a total of pounds 1m. Tesco also makes an annual pounds 1m donation to a selected charity.Reuse content