Five months after the Premier Foods business switched exclusively to British-sourced wheat, Hovis said the uplift was evidence consumers preferred UK-sourced produce.
"We are really pleased with the uplift, which is consistent with qualitative feedback we have received from consumers," said marketing director Jon Goldstone.
The news came as Hovis launched a £5m TV advertising campaign to support its new Hearty Oats loaf, which it predicted would generate a massive £30m in first-year sales.
Kicking off on 4 June, the ad takes a similarly nostalgic theme to the brand's famous Go on Lad push and charts the life of a mischievous schoolgirl from her childhood in the late 70s to the present day.
Goldstone described it as "a juxtaposition of nostalgic sentiment done well with new contemporary product positioning", and said it would provided some much-needed flair to the fmcg television advertising scene.
"There is nothing particularly special out there at the moment," he said. "In fmcg history there have been some fantastic ads but this is very far from being a golden age and is rather lacklustre. But our new ad has Hovis's signature nostalgic flair and really drives home the message that Hovis Hearty Oats is a healthy breakfast option."
He highlighted the "critical" timing of the initial advertising burst, which starts in the last week before the World Cup kicks off. "It's a dynamite week for advertisers as it's the final of Britain's Got Talent, the beginning of the last Big Brother and a Corrie special," he said.
"No-one wants to go head-to-head with the World Cup and, more than ever, marketing investment is under the microscope from a financial perspective. A lot of businesses don't have patience with advertising that doesn't pay back within the first month."