Trouble is they mostly don't talk to each other before they do it. I can cite five sources for figures on residential completions and rarely have I seen them agree. Where accuracy of data is concerned, you would think these people had learned their trade up in Beijing at the National Statistics Bureau.

And I don't expect things to change. This is government after all. If one department proves right then another has proved wrong and government is never wrong. It just wouldn't do.

I think Carrie Lam's basic reason for obstinacy here is that she thinks developers are not telling her the truth about supply, that they just want a return to the good old days when a certain beknighted individual in the most senior ranks of government was known as the Secretary for Developers' Profits.

It's a widely held view in government. Put up a piece of land for auction and the developers will collude at the auction to avoid competition between themselves. The public purse will then be shortchanged on the price.

The remedy that the bureaucrats have come to is the application list - a list of sites that they are willing to release piecemeal for sale but not until they get a bid that at least matches their reserve price and they won't tell you what that reserve price is. Even then the bidder must bid for the site again at public auction.

It certainly gets around the problem of collusion among developers but it doesn't get around the problem that the government may set the reserve prices far too high, which the developers say it routinely does. Every few months they sing this song again. Ms Lam has now just sung the government refrain again.

She has also swung into the second stanza, which consists of reciting figures about supply and vacancy and flats under construction, all of it to the general tune that there is no shortage and those fellows in the development business are having us on.

And this is where we get into the business of whose figures to believe when there is too wide a range of figures out there. I generally think the developers are right but I also think we have to put this into the context of longer-term slowdown in demand.

The straight supply figures (the ones I think most trustworthy) certainly indicate a slowdown. As the first chart shows, we are at record lows in supply of new flats, a bare 17,000 a year of all types. Relative to the size of our economy new supply is less than a tenth of what it was 25 years ago.

But the second chart tells a different story. It says that growth in the number of households is slowing down in line with slower population growth and that this is in turn matched by a slowdown in the growth of the housing stock.

I wish I could be more certain of these numbers than I am. I'm happy with the household figures but that stock of total homes is on a best efforts basis. All I will say is that I think the trend is right, that the two really are in step and that the margin of households over homes has been roughly constant since we finished the job of rehousing squatters.

This could mean that both the bureaucrats and the developers are right. Yes, there has been a slowdown but this does not mean that there is a shortage.

And there is one positive aspect to the developers' complaints about the scant supply for new development land. They have had to settle more for old development land, for redevelopment projects, which is otherwise called urban renewal and which most people think a good idea.