The latest headline figure from Professor Cheung's bureau is that 480,000 new units will be built in the next 10 years, 10,000 more than in a previous plan.

That is a worthy goal, but the problem, as always, is where to get the land and who will pay for it.

"If we shelve large-scale new developments, avoid increasing density, give up rezoning, reclamation and land resumption," he writes, "then where can we look to for releasing the much-needed land to meet our target of 480,000 new housing units in the coming decade?"

He warns if we "lack the guts to accept a trade-off between housing development and keeping various lands untouched, we are doomed to failure."

Most people realise more rezoning, reclamation and land resumption are inevitable if we want to increase land supply. But these should not be the only solutions. There are others:

• Crack down on wealthy public housing tenants. There is no doubt that a high proportion of public tenants have enough income and assets to be disqualified from continued occupation. A significant number own private sector flats. But housing officials are loath to determine the extent of this rule-breaking because it would mean enforcement.

• Tax the developers' huge land banks that spread across the New Territories as well as empty flats. By allowing developers to hold on to vacant sites without incurring any cost, they are able to develop and sell only during rising markets to maximise profits, thereby encouraging high prices.

• End the "small house policy" in the New Territories to free up land and facilitate urban planning.

• Speed up the conversion of old industrial buildings into residential sites but with fair land premiums.

Unfortunately, our officials prefer to call on the public to make sacrifices rather than taking on vested interests.