Heffer on Expenses

I sometimes think that Heffer is off the mark, but he's quite brilliant here on MPs expenses. But one passage got me thinking:-

Of course, if you don't want to stand again, you can tell Sir Thomas where to put his repayment demand. He probably wouldn't have any legal recourse if you do; and you won't care that the public thinks you a crook, because you don't need their votes any more.

Is this going to give us some more data on how bad the Labour defeat will be next year? Any MP that refuses probably know that their seat is sunk already, so see no reason to pay it back