AFTER Brexit, would an independent Scotland need what has been dubbed a “hard border” with the rest of UK? The answer is a definitive no.

Why can we say that so definitively? Because we both bring over 30 years of experience working for what used to be HM Customs & Excise, and have since been employed as Customs international consultants across the world.

All of that experience tells us that the UK Government would have to be on a kamikaze mission to want to hamper the smooth transit of goods and people on the Scottish-English border. The sensible comments from Brexit secretary David Davis MP on the Republic of Ireland-Northern Ireland border suggest London has not entirely lost leave of its senses in that respect.

The “hard or soft border” issue is just one of the questions that we have tried to find answers to in our new report as part of the Common Weal’s White Paper Project. Razor-wire fences and watch-towers are Unionist dystopian fantasy – but that’s not to say there are not crucial debates Scotland does need to have about its approach to borders and national sovereignty after independence.

A vital one is what sort of Customs regime Scotland would have.

Customs is the arm of government that is responsible for the control of flow of goods, and for collecting tariffs on those goods.

In the UK, Customs work has been systematically undermined since Gordon Brown amalgamated HM Customs & Excise with the Inland Revenue in 2005. Since that time, the UK has effectively stopped doing Customs work, over-prioritising the issue of immigration through UKBF, and the consequences of that are severe but not widely understood.

If you think about the indirect taxes the UK levies – like duty on fuel, alcohol and tax on sales (VAT) – Customs is a key part of every country’s revenues. In the UK this amounts to 39 per cent of all revenue. The undermining of Customs work is a key reason why the tax gap – the difference between what we should receive in tax revenue and what we don’t due to avoidance, evasion and debt – has grown, according to tax expert Richard Murphy, to an enormous £120 billion. A huge £40bn of that comes from the “shadow economy”.

There is no reason why an independent Scotland has to replicate the UK’s mistakes. We have estimated that one-third of the tax gap in Scotland could be closed quickly, raising an additional £3.5bn for the Scottish Government’s coffers.

A big part of achieving that would be through setting up a fully effective Customs & Excise division within Revenue Scotland, the Scottish tax collection agency. We estimate that 800 staff would be necessary in local offices throughout Scotland for full coverage. Taxpayers would get bang for their buck – Customs officers bring in revenue based on 1p for each £1 collected.

The Customs division would achieve this through a “smart borders” approach which means that the majority of Customs controls would occur inland, often near transit depots for efficiency. An arbitrary line on a map is not the principal, smart place to carry out border controls. France collects 90 per cent of its Customs/taxation through post-clearance Inland controls.

On the coast, Customs officers would deploy maritime assets to patrol and protect our borders using flexible, mobile Customs teams.

This work isn’t just important for revenue – it is also vital for keeping us all safe. The smuggling of drugs, weapons, illicit tobacco and alcohol using Scotland’s coast line is a long lasting and serious problem, affecting communities across Scotland. The UK has ignored its damaging impact. Customs officers, working alongside defence and police services, are crucial for the protection of society.

We propose a National Defence Academy to act as a headquarters for co-operation between these services and support educational development. This is an approach to defence that is serious about the real challenges Scotland faces.

There is no reason for independence supporters to fear the issue of an independent Scotland’s borders – in fact, our experience tells us there are significant opportunities to correct the UK Government’s disastrous mistakes.

Bill Austin and Peter Henderson both have more than 30 years’ experience in customs and excise and work as customs consultants to governments across the world