Yorkshire Building Society said it was starting to reap the benefits of its merger acquisitions after recording a 30pc boost in operating profit to £107.5m.

The YBS group's financial gains came as new lending rose 50pc in the first six months of the year, while net lending grew 179pc to £1.3bn.

The performance was partly boosted by the success of the Norwich & Peterborough –which merged with YBS in 2011– which continued to grow both its mortgage lending and the customer base linked to its current account.

The mutual said letters would be going out imminently to offer redress to customers after YBS was hit with penalties by the Financial Conduct Authority (FCA) last month for not being clear with inexperienced customers over investments that had almost zero chance of achieving maximum returns.

Chris Pilling, Yorkshire Building Society Group's chief executive, said mutual had learned from its mistakes and still had a superior customer satisfaction record compared to the big banks.

He added that the mutual decisions to buy or merge with a number of mutuals – including N&P and Egg – was now fuelling sustained growth.

'These exceptional results reflect our ongoing success as a business which proudly puts mutual values at its core,' he said.

'Achieving good levels of profit allows us to continue to invest in the future of the Group and make our offer to customers even stronger, for example ensuring a smooth transition to comply with the new Mortgage Market Review (MMR) rules with fully trained advisers available across our branch network and via our telephone contact centre.

'We have also successfully delivered in our core business areas – completing more than 16,000 mortgages, opening more than 100,000 savings accounts at a time of historically low interest rates, growing the N&P current account customer base and continuing to provide no-obligation financial advice for all across our branch network.'

Elsewhere, total mortgage balances of £30.8bn, with 94pc of mortgages funded by savings balances and reserves.

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