ScottishPower has shrugged off a 34 per cent earnings drop fall in its renewables division, due to lack of wind, and said it is in its busiest ever wind farm construction phase.

Meanwhile Ignacio Galan, the Spanish president of parent company Iberdrola, has entered the Brexit debate with an optimistic assessment of the UK’s outlook for inward investment.

Mr Galan, commenting on the group’s first-half results in Madrid yesterday, said: “The UK actually now has an opportunity to take additional measures that would encourage and attract new investment in to the country.”

Bilbao-based Iberdrola, Spain’s energy market leader, said it would meet this year’s earnings growth target of around five per cent, despite the impact of exchange rates and one-off factors, and expected net profit to rise at a similar rate.

“In terms of Brexit, Iberdrola’s significant currency and geographical diversification will offset any possible impacts.”

It said a 1.4 per cent rise year on year in its gross operating profit to £3.89 billion, and a recurring net profit up 13.8 per cent to £1.43bn, was due to good business performance and lower financial costs.

But a lack of wind meant its renewables business saw net earnings fall by more than a third compared with a year ago. to £116.6m, with the second quarter adding only £32m.

ScottishPower Renewables said the performance was “primarily driven by reduced wind output in the first half of the year” which was down 26 per cent, adding: “This is measured against a record output for the same period in 2015, which was in fact a 27 per cent increase on the equivalent 2014 figure.”

Last December ABO Wind UK scrapped plans for a Highland wind farm because wind speeds were too low. But ScottishPower says its sites are “based on years of monitoring the wind conditions on that site, and the UK and Scotland have got some of the best wind resources in the world and certainly Europe”.

Keith Anderson, ScottishPower’s chief corporate officer, said: “We remain on track to invest £1.3 billion in the UK this year. In Scotland we are currently building nearly 500 megawatts of new wind power across eight projects, which is our busiest ever period of construction.

“This programme will see us go above two gigawatts of installed wind power capacity, enough to meet the annual electricity demands of over one million homes.”

The lion’s share of the UK spend is in its £2.5bn wind farm in the North Sea off the Suffolk coast.

The group, which employs most of its 6,600 UK staff in Scotland, said SP Energy Networks recorded a two per cent fall in net earnings (EBITDA) to £404.5m. “These slightly lower returns are as anticipated, based on the phasing of investments,” the company said. It supplies 5.4m domestic and business customers in the UK through infrastructure investments agreed eight years ahead. A new investment programme for its distribution network began in April last year.

The retail and generation business reported a one per cent uplift in net earnings to £206m. Higher gas output and lower costs were offset by lower earnings in rental, driven mainly by milder weather and higher non-energy costs.