If you have a bit of cash, take it with you on a plane to Taiwan. In Taiwan, what is called the parallel economy may comprise 40% of the whole economy, according to government officials speaking privately. Taiwan has an underground futures market, an off-exchange stock market, a black-market foreign exchange network and an underground banking system - all highly efficient.

The return is government guaranteed because most black-market loans are made against post-dated cheques; your money is in effect, government guaranteed. To a point. Like most EU countries Taiwan has adopted the practice of guaranteeing small-amount cheques. Regardless of whether there are funds in the account or not, the bank on which the cheque is issued will redeem it up to a maximum value of 5,000 Taiwan dollars. For larger loans, protect yourself with several 5,000 Taiwan dollar cheques, or put your trust in the borrower.

Before 1987 failure to pay at maturity was a criminal offense punishable by imprisonment. Today, bouncing a cheque is only a civil offense, as long as intent to defraud cannot be proved.

The black-market lending industry is so well established that Taiwan's Central Bank of China publishes monthly statistics on the prevailing interest rates.

Currently, black market interest rates are around 2% a month, according to central bank figures. But reports in Taiwan' newspapers, backed by market sourses, say that rates can range up to 6% a month. When we visited, we placed some of our "suitcase cash" on the black-market, government guaranteed. After a month, we got it all back, plus a nice three per cent interest. According to the concerge of our hotel, had we been willing to venture into unsecured black market lending, he could have got us 6%. Have you got your calculator handy? Six per cent per month equals a cumulative annual interest rate of roughly 90%. Few other places worldwide can beat that. And none can offer at the same time a stable government, low inflation, sound money policies and no real exchange rate exposure.

The Taiwan secret for doubling your funds in a year, tax free, is probably our best advise for those who want to venture into the black market. In all other countries, the black-market is a shady, unregulated and very risky place where newcomers routinely lose their shirts. In Taiwan, it is highly efficient (more so than the official markets) and so open that everybody knows what's going on. Choose between the underground futures market, the off-exchange stockmarket, the black-market foreign exchange network and the underground banking system. All highly efficient and all run by reputable firms that don't go bust overnight and don't cheat innocent foreigners.

If you want to operate on your own, not dealing through middlemen, you can always open a nightclub in Taiwan. Don't laugh. For one thing, everything remotely western is bound to bring in the crowds. But even if you fail to attract a single soul, fear not, you will still make a bundle. Fact is, nightclub owners in Taiwan make most of their money being illegal bankers. This is done on the club's credit card account. The nightclub simulates a purchase but instead gives the "customer" cash, then collects from the credit card issuer. Using this system, your money will be banking in what amounts to the safest country in the world. You will be making five times your normal interest rate. And with a local partner, a Taiwanese or an expat living in Taiwan, you don't even need to stay on full time to look after your funds. This one little secret netted us £60,000 last year alone. When in Tainan, Taiwan, ask American expatriate Kevin Nelson for advise. He is married to s stunning Taiwanese woman, speaks the language fluently, has been living there since the mid-eighties and has lots and lots of connections.