So let's give it a go.

Gold, frankincense and myrrh were certainly highly prized 2,000 years ago; they were undoubtedly the luxury goods of the age. Gold, of course, is still familiar to us today; frankincense and myrrh perhaps less so.

Frankincense is the fragrant resin of a scraggy shrub that grows high on the inaccessible and inhospitable mountains that range the border of the Omani province of Dhofar and the notoriously-lawless Yemeni province of Hadramaut.

In the ancient world, frankincense was valued for the sharp and heady scent of its smoke and widely used in sacred rites. Its religious use is rarer today but the resin is still harvested as an ingredient of the perfume Amouage, a scent so blisteringly expensive it is sold in solid gold bottles.

Myrrh, another resin, comes mainly from the Horn of Africa. In the ancient world it played a central role in funereal rites, not least because its heavy sweet smell when burned is powerful enough to mask the odour of corruption.

We know that all three - gold, frankincense and myrrh - were certainly pricey 2,000 years ago but working out just how expensive is tricky.

Let's start with gold. Unfortunately St Matthew does not tell us how much gold the wise men gave. But it is reasonable to assume, since they were intent on venerating a divine king, they would not have wanted to appear stingy.

If we assume that the standard weight for golden royal regalia is the 42 ounce Sovereign's Orb of the British crown jewels, we can imagine that the wise men's gift weighed at least as much. In metric terms that means 1.3 kilograms of gold, valued today at a shade over US$34,000; generous certainly, but not beyond the bounds of possibility for those anxious to curry favour with a god-king.

Of course, values were different then and unfortunately price data for First Century Palestine are sketchy.

Sketchy is not quite the same as non-existent, however. St Matthew also tells us that roughly 30 years later Judas Iscariot was able to buy a field near Jerusalem with the 30 pieces of silver he received for betraying Christ.

The coins in question were half shekels from the temple treasury and each contained roughly seven grams of silver. In the ancient world, fields came in standard sizes of 100 cubits by 100 cubits or roughly 2,500 square metres.

So 210 grams of silver was sufficient to purchase 2,500 square metres on the outskirts of the old city of Jerusalem. If we assume that the relative value of gold and silver has held steady at 57 to 1 ever since, then the wise men's golden gift would have been able to purchase an impressive 882,000 square metres of property near Jerusalem.

A quick trawl of the internet reveals agricultural land in Israel being offered for sale today at US$44.27 per square metre. That means that the wise men's gift of gold to Jesus would have a purchasing power in 2007 of an astonishing US$39 million; no small present.

The internet also tells us that frankincense can be bought today for US$100 a kilogram and good quality myrrh for something similar. But it is fair to assume that fragrant gums are a debased currency today. In the ancient world, the transport costs alone would have been ruinous. Certainly incense was costly enough for Leonidas to rebuke a young Alexander the Great for his extravagance when he burned an entire handful of myrrh.

In all probability we can assume from St Matthew's ordering of the words 'gold, and frankincense, and myrrh' that he felt the gift of gold to have been the least impressive of the three.

Working on that assumption, we can estimate that the current purchasing power of the wise men's gifts to the baby Jesus would be somewhere over US$120 million.

That sounds a lot, but when you consider that it is less than a fifth of what the Hong Kong government plans to spend on its new headquarters, then you must conclude either that the wise men were being somewhat miserly with their presents, or that Donald Tsang has got ideas far above his station. Happy Christmas.