Bad housing wrecks lives
There is lots that could be written about the sheer misery caused by bad housing and overcrowding. But more powerful than any amount of statistics is a short (8 minute) film which Shelter got made recently, showing the experience of two families in housing which is manifestly unsuitable for their needs (though it meets the legal definition to be deemed adequate). You can watch it here
There are millions of people in similar situations to those of those two families, which should be a useful reminder for those who need it that there is more to the debate about housing than preserving the Green Belt or helping young professionals be able to buy their first property - it would make a real difference to have housing policy based on those in most need, rather than the most vocal.
More info about Shelter can be found here