I'll start by saying that I think it is quite reasonable for MPs who represent constituencies away from London to be able to claim sufficient allowances to enable them to stay in reasonable accomodation in London during the week.
There are issues with how they do that, but some allowance for it is reasonable.
But the idea that an MP representing Brent, a few stops up the Jubilee Line from Westminster, can claim for a second home while also owning a family home in Stratford, beggars belief.
And as my old mate Hywel Morgan has found out, the comparison between different MPs who all represent constituencies near each other in my old stamping ground of North London makes very interesting reading.
One of the issues here is that if they are using the allowance to pay off a mortgage the taxpayer is effectively buying a second home for them which they will be able to either rent out or sell off.
Whether or not this is technically within the rules, it certainly isn't right.
[Declaring my interest: I work for an MP outside London for 25% of my working week]