They may not be like you and me, the rich (although, seeing as I’m arguing for transparency I should disclose that they are a little more like me; few become tax barristers only for love). But the factors operating on us when we prepare our tax returns – fear of exposure and penalties coupled with a touch of moral imperative – are the same as the factors operating on them.

If you want a tax system that works, you need decent visibility between the income or gain giving rise to the liability to tax (what us lawyers call the “source”) and the person whose liability it is. You need good sightlines to connect the two. With this transparency in place, taxing authorities can threaten – in a meaningful way – the sanctions required to coerce the unwilling. Without it, the threats signify nothing. And if we want to tackle evasion, we need to work to ensure those factors operate with maximum vigour.

HSBC files show how Swiss bank helped clients dodge taxes and hide millions Read more

If you’re a tax haven, you measure success by the amount of foreign cash coming in year on year. You’re in competition with other tax havens to induce that cash to come to you. So how do you create the most accommodating climate? Take Switzerland as an example. It benefits enormously from a reputation for political stability – it’s all very well stashing your capital in Panama to save tax, but you have to be reasonably confident it will still be there when you come back for it. But Switzerland also has the selling point whereby breaches of its banking secrecy laws attract a criminal sanction. “Come to Switzerland,” is the pitch, “we’re not Ruritania. We’ll never tell your government that you have assets here. We can’t – we’ll be sent to prison.” Just think about that: what are the “good reasons” for criminalising disclosure?

It was this thinking that lay behind Labour’s recent call for “beneficial ownership registries” of companies. It’s all very well knowing that a vault of cash in Switzerland is owned by a shell company – but who owns the shell company? The coalition government has also recognised this in pushing hard internationally on “automatic information exchange” provisions to enhance the speed and quality of information given by tax havens to proper countries. It might be politically inconvenient to acknowledge it, but when it comes to legislative measures to tackle evasion and avoidance, the coalition has been genuinely radical.

However, let’s not kid ourselves: these initiatives – and others – may throw shafts of light into the vaults, but the basic tension between the interests of tax havens in protecting their domestic economies and other countries in securing their proper tax revenues remains. And it will clog all attempts at improvement. Is this desirable? Far from it. But changing it will take real political focus, including the sorts of unilateral action – for example, in respect of British overseas territories – that Labour has proposed.

If you choose pragmatism over idealism, the one thing you absolutely have to do is deliver. And Britain hasn’t.

So, sanctions. On this we’ve really dropped the ball. Faced with tax evasion – which in the UK amounts to about £5bn a year – you can get down off your high horse and take the pragmatic course of getting the money in through tax amnesties, or you can threaten to come down hard on evaders. We’ve made a very clear policy decision in favour of the former. As treasury minister David Gauke said on Monday in parliament: “In most cases disclosure and civil fines are the most appropriate and effective intervention. That is how HMRC has approached the receipt data from leaks and whistleblowers including the Swiss HSBC data shared with the department in 2010.”

But if you do choose pragmatism over idealism, the one thing you absolutely positively have to do is deliver. And Britain hasn’t. Back in 2011, the UK signed the Swiss/UK tax cooperation agreement, which offered an opportunity for tax evaders with Swiss accounts to come clean without criminal sanction or heavy penalty. We predicted revenues of more than £5bn over six years. By now we would have expected to have received about £4bn but we’ve received a little over £1bn.

The HSBC files is another example. As the Guardian has reported, the UK received information on about 6,000 individuals and businesses and recovered tax and penalties of £135m. France and Spain – both with fewer billionaires than the UK – have recovered £188m from 3,000 and £220m also from 3,000 respectively. Closer analysis of the French figures reveals that its revenue authorities have yielded three times as much from bank accounts held by French residents as HMRC has from accounts held by UK residents. France is also prosecuting HSBC for money laundering offences.

Tackling this sort of tax evasion is labour intensive. It takes time to piece together the story from tiny fragments of evidence. But since the coalition came to power, HMRC’s full-time equivalent staff has been cut from 96,000 to fewer than 60,000. And its budget has been cut by 25% – with more reductions to come. It is difficult to see how this could not have had an impact.

And when it comes to prosecutions, we can’t ignore that winning tax evasion cases, as with much white collar crime, is incredibly difficult. The law and facts are just too complicated to get a jury over the line on beyond reasonable doubt. But the status quo – effectively of impunity for wealthy tax evaders – plainly isn’t good enough.

A government that was serious about tackling financial crime would change the law to enable specialist juries – or even abandon jury trials altogether. So increased pressure on tax havens, and enhanced sanctions for evaders, may be more aspirin than antibiotic, but it will help.