And of course it is a statistical minefield. The definition of homelessness is problematic, because it ranges from rough sleepers, who are phenomenally difficult to count accurately, through families with young children who have lost their income due to sudden unemployment through no fault of their own, to young people who are not getting on all that well with their parents and would like to leave home.
Shelter has a lot of useful stats. In 2009/10, more than 62,000 households were found to be homeless by English local authorities.
Next, Shelter has found that there are 279,000 long term privately owned empty homes in England
So, at first glance, there are 4 times as many empty houses as there are homeless families.
However, the reality is more complex. Empty houses are not necessarily in the same locations as homeless families, and some are at present unfit for habitation. Shelter estimates that 1,000,000 more homes will be needed over the next five years.
Note that the private long term empty properties are matched by numbers of second homes and local authority "voids". So the number of under-used houses approaches 559,000. About 9 times greater than the number of statutory homeless people.
I'm not suggesting that second homes should be expropriated, but it would not be unreasonable to apply swingeing taxes to second homes and long term empty properties in order to encourage their return to the housing market, and to hypothecate these extra taxes to funding solutions to homelessness.
In my 6 years as an elected (Green) member on Woodspring (now North Somerset) Council I got Environmental Health to review their list of empty properties. Some of them were already back in use (i.e. the list was inaccurate) but we did get a useful number of homes back into use. Every little 'elps, as my granny used to say.
One metric that I came up with in my book, Bills of Health was the concept of the Housing Roof Year - HRY, the amount of money required to keep a homeless family under a roof for one year.
The figure for keeping a family in temporary accommodation when I wrote in 1996 was £10,000.
I calculated in Bills of Health (p 92) that a HRY obtained through building (or refurbishing) a property would come to £1000.
Therefore the taxpayer could save 62,000 x 9000 = £558,000,000 per year through providing an adequate amount of decent new or refurbished houses. Half a billion a year. Not to be sneezed at in this time of austerity. George, are you listening? (No of course not).
Oh, and 6% of the NHS clinical budget is spent on trying to treat illnesses caused by sub-standard housing. That is about £6 billion.
Why is the Treasury not interested in providing a humane, cost effective answer to the housing problem? I can think of two possible answers.
1) They are very very stupid,
2) The landlords who profit from providing Temporary Accommodation (and also receive Housing Benefit) are in some way able to persuade the governing parties that the present arrangements are perfectly satisfactory.
So, in conclusion, I was right to say that there are more empty houses than homeless families.
The situation is indeed more complex than that, but a rational and humane housing policy could save us a cool £6.5bn per year.