Dunsmore will be succeeded at the Magners brewer by finance director and chief operating officer Stephen Glancey.
Glancey said: “There is no change in strategy at all. You could not put a cigarette paper between us in terms of our view of the business.”
First-half operating profit was up 7.8 per cent to €67.4m (£58.6m) compared with a forecast for €66.4m, while earnings per share were up 7.1 per cent.
“It is a surprise for the market. People are asking questions about what is going on,” Bloxham analyst Joe Gill said.
“But the numbers are reasonably solid, especially given the poor consumer background.”
Dunsmore said the company had decided to cut the amount of senior management capability after three years of significant restructuring. The interim dividend was raised 11 per cent to 3.67 cents.