Even during significant economic downturns, certain activities must carry on. Trade may come to a virtual standstill but trans-port networks continue to function. Due to landing-rights agreements and mail contracts, for example, scheduled air services must be maintained.

At the height of the Sars crisis, in 2003, I was on a flight from Australia with literally more stewards than passengers on board. Cargo and freight helped the airlines - and the broader economy - weather that storm.

There remain buildings in Hong Kong that stand as evidence of the impact of economic turmoil almost a century ago, and the ability of the cargo carriers of the day - shipping companies - to endure those hard times.

The 1880s and 1890s had witnessed what was then the world's most prolonged economic boom, as a wave of pioneering technology transformed life all over the globe.

In 1869, the opening of the Suez Canal reduced transport times from Europe to the Far East from three months to six weeks. Goods could be transported more economically; increased volume improved margins, lowered prices and drove up demand.

In the 1870s, overland and submarine telegraphic communications - the e-mail of that age - meant markets could suddenly operate in almost-real time. Before cables connected Hong Kong, via the aptly named Telegraph Bay, with the wider world, local business decisions were based on educated guesswork. Near-immediate responses then became possible. Electricity and the introduction of telephones completed the circuit.

Artificial ice-manufacture technology, meanwhile, meant predominantly agricultural countries such as Australia, New Zealand and Canada could export perishable produce. Adverts for frozen mutton, refrigerated butter and cold-storage fruit appeared in Hong Kong publications from the late 1880s. In turn, farmers in those countries had greater disposable income to buy mainland-made luxury goods, such as silk and porcelain, traded through Hong Kong.

Medical advances further improved life while prolonged international peace, minor conflicts notwithstanding, also contributed to boom conditions.

But when the bubble burst with a massive stock-market crash in 1904, the global party known as The Gay Nineties ended abruptly. The years 1906 and 07 saw banking crises and state intervention to quell rising social unrest.

Before the first world war, British academic John Maynard Keynes' economic theories gained a foothold and governments started deficit spending. Subsidising inefficient industries to keep people working was considered cheaper and better than providing relief for the poor.

Brick-kilns in economically depressed parts of England were one prominent example.

Overseas British territories also affected by economic depression participated in this process. British-made bricks were transported as ballast on shipping lines that - for mail-contract reasons - had to make regular sailings. They were then stockpiled at the other end for eventual use. British bricks were used extensively between about 1904 and the outbreak of war. Government-led capital works projects helped kick-start business confidence in Hong Kong and other Eastern port cities such as Singapore and Penang, Malaysia.