Warburtons has done it with bread, Nichols is doing it with Vimto and now another northern company, AG Barr, is attempting to drive up sales in the south with a £15m investment in Irn-Bru.

AG Barr hopes the cash injection, which it claims is its biggest-ever single investment in Scottish staple Irn-Bru, will initiate a "step change" for the brand in England and Wales.

Although two-thirds of Irn Bru's sales come from Scotland, in the past year its sales in England and Wales have increased 18% to £25m [Nielsen MAT 20 March 2010] a value that Barr claims will double within three years.

The £15m will fund a new national TV campaign for the fizzy drink and its continued sponsorship of Sky Sports' Rugby Super League coverage.

The new ad Irn-Bru's first in England and Wales for three years hits television screens next month and is online now.

It features a Disney-esque cast of animated animals traipsing through the countryside, but ends with a dark twist.

Last month, AG Barr, which also owns Rubicon, posted an overall sales growth of 18.7% to £201.4m, with profits up 20% [52w/e 30 January 2010] .

"Over the past three years a lot of the other major players in the market have been more interested in ­developing still drinks, but we have very much focused on carbonates and have seen the benefits," said head of marketing, Adrian Troy.

"We've driven a lot of distribution growth outside Scotland and we're now taking advantage of that by putting the consumer support in."

Tristan Connell, managing director of advertising at The Bank agency, said it was the right time to ­invest. "As Pepsi takes over from Coca-Cola in the on-trade market, and with the recent growth in the soft drinks sector, there is much to play for," he said.

"In that respect it is timely for Irn-Bru to up their stake and ensure they stand out in a crowded and highly competitive marketplace."