The UK is one of the only developed economies not using a form of national ID card, research has shown.

Research for Sky News’ Sunday Morning with Trevor Phillips found that of the 38 OECD (Organisation for Economic Cooperation and Development) countries, just six – all predominantly English-speaking – do not have an ID scheme: Australia, Canada, Ireland, New Zealand, the United States and the UK.

Debate over digital ID cards reignited this week, following the latest intervention by former prime minister Sir Tony Blair.

Writing in the Daily Mail, Sir Tony argued: “Lower taxes, reduced spending and improved outcomes have often seemed like the Holy Grail of governing: desirable but impossible. Modern technology puts it within reach.

“Our present system isn’t working,” he added. “This is a time for shaking up. For once-in-a-generation disruption. Digital ID is a good place to start.”

Compulsory physical ID was one of the flagship projects in Mr Blair’s premiership, but plans were shelved by the coalition government before they could be introduced.

Mr Blair’s Institute for Global Change estimates the scheme would cost £1bn to launch and £100m a year to maintain, but could save the Treasury £2bn a year.

Separate analysis in 2019 by consultants McKinsey found ID cards could boost Britain’s GDP by 3% by streamlining bureaucracy and access to public services.

But opponents argue they pose risks to civil liberties and could lay the foundations for a surveillance state.

The implementation of ID cards varies widely around the world.

Cards remain only optional in most OECD countries, whereas Chile, Luxembourg and Turkey legally require citizens to carry ID at all times.

There seems to have been a move towards ID cards in recent years, with Norway, Hungary, Denmark, Japan and Lithuania all introducing them in the last 10 years.

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The UK government has given mixed signals over whether digital ID is on the agenda.

Speaking to Sky’s Trevor Phillips days after the election, Business Secretary Jonathan Reynolds said Home Secretary Yvette Cooper “would be looking at all the sources of advice” on the issue – only to reverse that in another interview hours later.

The government has since tabled legislation to help create “digital identities”, allowing people to opt in or out of having certain information, like their address or biometrics, on their digital record.

Ministers have made pains to stress these would be neither mandatory nor digital ID cards.

Australia started rolling out a similar scheme earlier this month, despite concerns over privacy and safeguarding.

On today’s Sunday Morning with Trevor Phillips, Trevor will be joined by Border Security Minister Angela Eagle, shadow home secretary Chris Philp, and journalist and historian Anne Applebaum.

Watch it live on Sky News from 8.30am, and follow along live on the Politics Hub.