The clunky technology underpinning Blighty's border control leaves the UK in concerning position post-Brexit, a National Audit Office report has found.
Border operations in the UK still rely on '90s technology that lacks modern functionality.
"The government's ambitions to seamlessly interact with citizens, and securely share information, are currently limited by historic investments such as the Casework Information System and Warnings Index (used by the Home Office) and the [Customs Handling of Import and Export Freight] system used by HMRC," said the report.
The government recognises the limitations of these systems and has started programmes to replace them, it noted.
But the National Audit Office previously said the Home Office's e-Borders project "vital to national security" will eventually cost the taxpayer more than £1bn and arrive at least eight years late.
Meanwhile, the CHIEF replacement system, designed prior to the EU referendum, may not be ready for March 2019.
Meg Hillier MP, chairman of the Committee of Public Accounts, said: "How the UK manages its borders has been a question of significant concern in the government's approach to Brexit.
"But this report from the NAO underlines the sheer scale of the task ahead. The government can't even get started on many of these challenges until we have progress on the exit deal.
"Add to that the Home Office's poor track record with projects like e-Borders and for all the government bluster about Brexit it's difficult to see how, practically, it will be able to deliver any of these huge changes in time."
The report noted some significant weaknesses, major contract disputes and high project failures in border management. The most notable failure was the e‐Borders programme, but other programmes have also delivered less than planned.
In 2017, the government still uses outdated technology, some border processes remain manual and there are significant gaps in data. In many respects, people working at the border manage in spite of these weaknesses but, even here, recruiting, retaining and deploying people in the right border roles remains difficult.
Last year more than 271 million people crossed the UK border by air (28 per cent of these at Heathrow), almost 22 million crossed the border by sea and just under 21 million left or arrived in the UK by train. Since 2005, passenger arrivals and the value of imports have increased 27 per cent and 46 per cent respectively.
The report identified a range of challenges that the government faces as it implements a new border management regime from March 2019, most of which will arise regardless of exit from the EU.
These include: an increase in border crossings, consistent with a trend to more mobility; an environment characterised by increasing and complex security threats; rising citizens' expectations and the test of new, digital ways of working; and the challenge of managing within constrained resources. ®