In October 2010, Boris Johnson memorably declared of the government's plan to cap housing benefit, "What we will not see and we will not accept [is] any kind of Kosovo-style social cleansing of London.
"On my watch, you are not going to see thousands of families evicted from the place where they have been living and have put down roots".
Yet now, just nine days before the London mayoral election, we have an example of precisely that. The BBC reports that Newham council is trying to evict 500 families on housing benefit to Stoke - 135 miles north - after concluding that it can no longer afford to house them in private accommodation.
Rents have risen steeply in the borough, the site of the Olympic park, and the housing benefit cap of £400 per week has exacerbated the problem. Yet this morning on the Today programme, housing minister Grant Shapps casually asserted that "rents are actually falling, they've been lower than inflation for some time". But even if we assume that rent increases are lower than inflation, that does not equate to them falling. For those whose pay has been cut or frozen (93 per cent of new housing benefit claimants are in work), rents are certainly rising. Research by Shelter, for instance, found that while the average London wage increased by 3.8 per cent in 2010-11, private rents increased by 6.8 per cent.
Labour MP Karen Buck, one of Westminster's foremost experts on housing, notes:
We know from London Councils that 88,000 households have private rents above the new limits for housing benefit and in theory these families were meant to find new homes in places like Newham.
Obviously, even before the housing benefit cuts have really began to bite we have seen that this policy will unravel.
The problem was both predictable and predicted. The inflated housing benefit budget, which now totals £20bn, is the result of a conscious choice by successive governments to subsidise private landlords rather than invest in affordable social housing. To cap benefits, then, is to tackle the symptoms, rather than the cause.
With signs that the Tories' political woes are hitting support for Boris (yesterday's YouGov poll showed that Ken Livingstone had narrowed his lead to just two points), this story comes at an awkward moment for the Mayor of London. If he wants to indulge in some more pre-election differentiation, now would be the time to do so.