The bridge will go directly to Hong Kong. The tunnel, I suspect, would end in a Guangdong politician's bank account.

But let's have a go at someone else today. The point about this bridge is that it is likely to make a success of the Hong Kong Airport Authority's purchase of a controlling interest in the moribund Zhuhai airport. The Airport Authority's game plan is obvious.

The Zhuhai airport is on the ropes with big debt and scant income. Refinance it, spend a little money to upgrade it to the latest standards, make everyone feel comfortable with the Hong Kong ownership and then bring on the budget airlines that almost everyone in China wants to start up these days.

Even without a bridge, the pitch could work - fly to Zhuhai on the cheap, have a fling at the Macau casinos, take a fast ferry to see Hong Kong, board a train or bus up to Guangzhou and then finish the circle tour back in Zhuhai to fly out on the cheap again.

With a bridge, the stakes in the game go up. The spoke will be in place to a hub in Hong Kong for quick transits between short-haul and long-haul flights, which may mean something as congestion at our airport grows. Zhuhai is also well placed to become an air cargo centre.

It doesn't impress Cathay Pacific's chief operating officer, Tony Tyler, however.

In the latest issue of the airline's in-house rag, he pooh-poohs the idea, saying that Zhuhai can never serve as a 'third runway' to Hong Kong as there is too much trouble involved for transit passengers. The two are not complementary.

Hong Kong, he says, should build its own hub strengths, meaning, I suppose, that he would not object so strongly if the link to Zhuhai were by air instead of road and Cathay Pacific or Dragonair had a decent share of the flights.

He makes a political point of it too: 'The Airport Authority making a purely financial investment in other airports is one thing. The Government is well represented on the Airport Authority board and can decide whether that is an appropriate way to invest taxpayers' money.'

Aw, Tony, I done you wrong. So you really do care about the taxpayers' money after all, do you? And here I thought that Cathay Pacific took an interest only when thinking up schemes for taking money out of the taxpayers' pocket, most recently during tough times for airlines in 2001 and 2003. My heartfelt, humblest, deepest, most profound and abject apologies etc. etc.

But we, with five airports in Pearl River Delta, are not unique. I can think of another urban conglomeration served by five airports connected by road and rail links.

In London, it works quite well. Although one company owns the three biggest, they all compete and are also complementary in their own markets.

Your choice is Heathrow if your company pays, Gatwick if it doesn't, Stansted for a cheap Ryanair holiday to Europe, City Airport for convenience because it's close to the office and Luton I have never used.

Rank them by share of their total passenger market and, as the two charts show, you get roughly the same breakdown as you do for biggest to smallest in the five PRD airports. There are differences I grant you but would British Airways have grounds to object if Heathrow were to take a stake in City Airport?

I am a taxpayer, Tony, and I shall tell you where my interest lies. It is in getting a decent return on my investment in our airport. One way to do that would be to charge Cathay Pacific more for landing rights. Failing this, a reasonable investment in another PRD airport with growth potential will do just fine.

And if you don't happen to have operations in Zhuhai, that's just tough luck for you. As a taxpayer it doesn't bother me.