The Census find 26 million spare bedrooms. It's so tantalising to compare that to the housing shortage and imagine shuffling families around so their housing better fits their needs.

Under-occupied doesn't mean never occupied. If the Census was taken on Christmas Eve, many of these bedrooms would suddenly be occupied by visiting relatives.

With WFH and hybrid working now increasingly common, a lot of the spare rooms are finding utility as home offices. Not as essential or as useful as a place to sleep, but not 0.

Compare it to cars. 65% of car trips are lone driver, i.e. no-one in the passanger seats. But the vast majority of car buyers, even childless motorists - don't choose a 2 seater. Those extra seats in the back are occasionally useful.

We also have such an illiquid housing market. 1.3 million houses are sold per year. That's less than 5% of the housing stock. Even if you changed housing occupancy incentives via taxation, it would take decades for these effects to feed through.

People also have sentimental attachment to their homes. It's not just square footage under a roof - it's their sense of place.

Finally, under-occupation is based on a definition of need. But that's not how markets work. People very reasonably want more than they technically need according to statistical analysis. And they use their purchasing power to give themselves that additional living space.

The counter to all that though: it's still 26 million spare bedrooms! That's a vast amount of housing space. Even marginal tax incentives to nudge homeowners away from under-occupying could have serious potential to rebalance housing need.

Campaigns like @FairerShare 's push for proportional property taxes are not just fair in their own right, but would start to reverse the tide on under-occupation and better balance our consumption of housing.

@DuncanStott I would add that we haven't built enough attractive new retirement properties for older people to move in to. There are some fantastic products out there, but not enough of them and so the attitude of the old unpleasant care home remains.

@DuncanStott An associated issue is that houses with a larger number of bedrooms are often bought to get additional space in the lounge, dining room, kitchen, yet a large two bedroom house is an oddity.

@DuncanStott 👍