The Prime Minister's invitation to representatives of other governments to attend an Anti-Corruption Summit in London looked like a good idea when he announced it a year ago.
Before, that is, he chose to insult two of the guests.
The gaffe has already drawn quick rebuttals from the two countries, with the Nigerian President claiming to be "shocked and embarrassed", while the Afghan embassy has described the comments as "unfair".
Given that these countries represent two of only four heads of government to confirm their attendance at the event, a diplomatic bungle is not the most constructive way to begin proceedings that require global cooperation.
Now the summit has arrived, other difficulties are starting to emerge.
Among them: Britain's relations with corrupt businessmen and politicians across the world, the role of "middle men" companies managing the affairs of doubtful overseas investors, the welcome the UK has given to those who wish to buy homes here, and the importance of UK overseas territories in the flow of offshore funds.
The Tier One (Investor) Visa Scheme has sold preferential rights to residence in the UK, in return for loans of £1m from 1994, recently increased to £2m.
The Panama Papers have provided more evidence about the doubtful origins of some of those granted residence, a number of whom have since been granted citizenship.
Malta sells citizenship in return for investment, as does Antigua – but it’s demeaning for the UK to do the same.
The Panama Papers have underlined the importance of Britain’s Overseas Territories in global tax evasion and money-laundering.
The British Government cannot hide from the disclosure that the UK has sovereignty over around a third of the world’s tax havens. The UK is undoubtedly in a unique position to lead on this issue and any attempt to dodge this responsibility is now inexcusable.
The attractions of the UK Overseas Territories lie in their British legal standards and the British-linked accountants and lawyers who advise offshore investors, under UK sovereignty. A previous British government imposed direct rule on the Turks and Caicos Islands to stamp out what it described as systemic corruption.
But this government refuses to use its sovereign authority to insist that these territories provide transparent information on who effectively own the thousands of shell companies they sponsor.
In the European Referendum debate, the European Court of Human Rights, the EU’s own Court of Justice, and the European Commission, are presented as major threats to British sovereignty.
Read more: Who leaked the Panama Papers?
Leave campaigners sadly ignore the far more immediate threat that the spill-over of corruptly-acquired wealth, with the illegal or marginally-legal practices that are imported with it, pose to our way of life.
The Spanish government has now launched a major prosecution against rich Russians resident in their country with links to organised crime across the former Soviet Union.
Those who claim to care about the defence of British sovereignty demand our government take similar action.