The UK accounted for 28% of profits at ScottishPower's parent Iberdrola last year, the group revealed, just behind the 30% of earnings from its home market in Spain. Earnings before interest, taxation, depreciation and amortisation at ScottishPower rose 3.7% to £1.2 billion in 2012, helped in part by a 7% rise in customer numbers.
Some two pounds out of five that Iberdrola is spending on investment is being directed to the UK, including a record £1.3bn this year, of which £550 million will go towards renewables.
Iberdrola chief executive Ignacio Galan said: "We are investing more here. 2013 will see a record investment in this country."
Six years after snapping up Glasgow-based ScottishPower for £11.6bn, he said its plans to spend £10bn in the UK over the next decade are akin to buying the company all over again.
Mr Galan said there was "more certainty than a year ago" over Government energy plans but he called for clarity in areas such as support for proposed gas fired power stations.
ScottishPower's chief corporate officer, Keith Anderson, said its UK renewable business, which is working on 35 projects, would continue its expansion. "There will be no hiatus," he told The Herald.
ScottishPower's approach contrasts with that of Perth-based SSE, owner of Scottish Hydro Electric, which has long warned of a possible investment hiatus, and last week said spending could "fall off a cliff".
Mr Anderson said pricing for onshore wind generation is certain up until 2017, so it will go ahead with projects such as the 96-turbine Kilgallioch wind farm in south-west Scotland which now has planning permission.
He said ScottishPower is also keen to press on with offshore wind farms such as West of Duddon Sands off Cumbria.
The Government's plan to unveil draft pricing plans for renewables in the summer and confirm them by the end of the year fitted ScottishPower's timetable, he said. But he said that if there are delays, the existing renewables obligation regime could be extended.
ScottishPower can afford to be slightly more relaxed than its rivals because, after building its first wind farm 21 years ago, it has got a large onshore wind presence. Its rivals tend to be more reliant on new capital-hungry offshore projects.
One area of concern for ScottishPower is capacity payments for conventional power. It has planning permission for three new gas power stations in the UK, including at its coal-fired plant at Cockenzie, East Lothian, which will close at the end of next month. Mr Galan said: "A power plant is not completed in 45 days but three years. We are doing our job in planning and design. But the go-ahead depends on the framework."
Mr Galan said he picked up an increased sense of urgency within the corridors of Government at the prospect of black-outs when old power stations are taken out of service.
Iberdrola saw profits in the Spanish market, where it supplies 10 million homes, plunge 36%, which it blamed in part on regulation. But continuing growth overseas, including at ScottishPower, which has 5.6 million retail customers, meant net profit ticked up 1.3% to €2.84bn (£2.4bn).
Its debt fell €1.4bn to €30.3bn after it concluded €850m of €2bn planned asset sales. This has allowed it to rule out the sale of a stake in its UK regulated power business, which houses its electricity distribution and high voltage transmission arms.
It also has cash to launch the buy-back of 2.4% of its shares.