tenantplus - before making sweeping statements condemning many, what would be your solution for uncovering and tackling tennacy fraud? At least one thing criminalisation has going for it is that it might actually be a deterrent for those who wilfully do it.
I was in housing management for many years and the evidence required to prove it is nigh on impossible to get. People will refuse you entry on unannounced visits, if you write ahead the proper tenant suddenly pops up, and ultimately top brass at HA's won't approve the massive legal costs as financially there's little benefit, if anything illegal subletters are perfect tenants, they know it's not in their interest to attract attention through ASB or rent arrears.
Regardless of people's circumstances, even if they are living on the breadline and the £200 a month profit they make subletting barely covers expenses, it is still a wilfull act and defrauds all taxpayers (cue rant abourt tax avoidance no doubt)
Oh, and increasing the social housing supply to make subletting less of an issue isn't an admissable answer to tackling the issue!!