Customer numbers were flat at 5.6 million, while it said other big firms have been shedding them. Gas customers remained flat at 2.2m and electricity at 3.4m.
The firm’s UK generation and supply earnings rose 8.5 per cent to €244 million (£192m) in first half, although generation fell by 3.8 per cent because of the knock-on effect of closure of Cockenzie power station.
The improved profits came despite lower retail customer demand for electricity and gas due to the relatively mild winter.
Hydro production from the group’s three hydro plants at Cruachan, Galloway and Lanark was up 26.7 per cent in the first half and the firm said it planned tocontinue building renewables capacity in the UK.
ScottishPower’s Spanish parent Iberdrola saw group net profit fall 13 per cent to €1.5 billion, which it blamed on a combination of the impact of regulatory changes in Spain and to last year’s comparators being raised by “one-off balance sheet revaluation of some Spanish assets”.