Sometimes a government does something so brazenly opportunistic that its pandering to certain sections of the electorate must be discernible from Mars. In its infinite wisdom, Britain's coalition government has come up with a stunt that may haunt its dominant Conservative Party for years to come.

In a nutshell, some genius (rumoured to be Lynton Crosby, the Conservatives' Australian campaign consultant) considered it a good idea to dispatch a van onto the streets of London emblazoned with a huge placard exhorting illegal immigrants to "GO HOME OR FACE ARREST".

Never mind that immigrants are probably already aware of whether their status is legal or not - or that some probably can't even read what's written if they aren't - reminiscent of the worst far-right-wing anti-immigrant language of the 1970s, the "racist van" has been widely lampooned as marking the moment Prime Minister David Cameron's cuddly mask slid off.

The move has been subsequently disowned by his party's Liberal Democrat partners and the Advertising Standards Authority is investigating whether it could incite racial hatred.

The van episode comes hard on the heels of a series of raids on Chinese restaurants from Cornwall to Scotland by UK Border Agency immigration officers, who have imposed fines of £10,000 (HK$120,000) for each illegal worker discovered. The China Glen restaurant in Livingston, West Lothian, faces a bill for £80,000 for its eight violations and the Sun Wah in Launceston, Cornwall, will have to cough up £40,000. A bit harsh for two tiny takeaways.

Chinese caterers have argued in the past that their cuisine requires specialist knowledge - or at least a lifetime of eating it - and that these skills can't be taught on the hoof to youths more accustomed to burgers and pizzas. However, hard-hearted politicians with an eye on the next election appear unmoved regarding the authenticity of their next chop suey. Raids are due to start all over again in November.

With a network of people smugglers run by Chinese masterminds recently uncovered in France and Spain, Chinese businesses have been made a primary target for British authorities. It's as though the government were going steadily prawn crackers.