The figures, generated by the Open Banking Implementation Entity (OBIE), only represent customers of the CMA9, the nine biggest current account providers in Great Britain and Northern Ireland.

The doubling in customer numbers mirrors similar growth in third party service providers. Currently there are 204 regulated providers, up from 100 at the end of 2018, who are fielding approximately 200 million monthly calls on bank account data.

Imran Gulamhuseinwala, trustee, Open Banking Implementation Entity, comments: “One million is a significant milestone, but by no means is it the end. Open Banking is about giving customers access to their data to rebalance the market in their favour. By creating greater competition, we are seeing innovation from new entrants and incumbents, which is leading to greater convenience and crucially greater engagement. We believe 2020 will be the year when adoption of Open Banking financial services really takes off.”

The Financial Conduct Authority recently issued a call for input on proposals to extend open banking rules beyond payment account data to a wider range of products in the general insurance, cash savings and mortgage markets, under a new model billed as 'open finance'.

Christopher Woolard, the FCA's executive director of strategy and competition, states: “The UK has led the way internationally in the development of Open Banking, which supports our objective of promoting effective competition in the interests of consumers. As we look forward, we also want to consider the potential benefits that could come from giving consumers and businesses control over a wider range of their financial data."