I'm sure that it's quite possible that Hazel Blears did correctly and by the rules classify those London properties as her second home.
However there are fundamental principles laid out in the Green Book that govern every single expense claim that they allow.
One rule is that "the Additional Costs Allowance (ACA) reimburses Members of Parliament for expenses wholly, exclusively and necessarily incurred when staying overnight away from their main UK residence (referred to below as their main home) for the purpose of performing Parliamentary duties. This excludes expenses that have been incurred for purely personal or political purposes."
Another is that "you must avoid any arrangement which may give rise to an accusation that you are, or someone close to you is, obtaining an immediate benefit or subsidy from public funds."
What does moving homes three times, getting us to pay for them to be refurbished and avoiding paying the capital gains tax by telling the taxman they were her main home while claiming expenses as though there were her second suggest?
Was moving three times, at our expense and her profit, "necessarily incurred" "for the purpose of performing Parliamentary duties" or rather for "purely personal" purposes?
By the very fine detail of individual rules MPs might claim that they have not broken anything.
However many of them have completely ignored the overriding principles that govern the entire expenses system.
Don't be distracted by the details of individual rules but look instead at the Principles that they chose to ignore. That's the key to all of this and it is for ignoring those very principles that they are being asked to pay the money back.
And as to the MP that claimed for a Duck House, a floating one at that, consider that they are also told that "you should avoid purchases which could be seen as extravagant or luxurious."
That speaks volumes as to their attitudes to the expenses system.