John Lewis will launch its biggest ever TV advertising campaign on Friday to push its “never knowingly undersold” policy.

The six-week campaign, which has cost the department store group £6m, will mark the first time the retailer has dedicated a TV and press campaign to its commitment to quality, price and service. 

The TV advertisement, which will air for the first time on Friday at 7.45pm during Coronation Street, will feature a female character growing up with John Lewis from when she is a young child until she is a grandmother.

The retailer said the ad would reinforce the idea that John Lewis has made a lifelong commitment to give great quality, fair prices and excellent service to its customers.

The campaign, which consists of one 90-second, one 60-second and four 10-second TV ads, also features two John Lewis staff as two delivery drivers.

The TV campaign will be supported by national print advertising.

Craig Inglis, director, marketing at John Lewis, said: “The key message the campaign conveys is that John Lewis is always there for you, whether you are setting up your first home, having a baby or just love shopping with us. We are there for all the important times, big or small.”

He added: “For a long time Never Knowingly Undersold has been perceived as just a price promise, but it’s more than that: it’s about the total value we offer our customers, about the quality of the products we sell and the added value customers receive with the service our partners offer.”