The idea that David Davis's self-imposed by-election in a Tory seat that Labour could never expect to win will provide some sort of public verdict on the 42-days decision is utterly ludicrous. Given that the Lib Dems will apparently not run, it is grandstanding of the highest order by Davis. The idea that six rather than four weeks is a fundamentally different order of loss of liberty is quite absurd. What the new law does allow, with serious safeguards, is some flexibility for the police in the most serious terrorist cases.
If Davis gets a good result, as must be probable given constituency politics, Cameron and those in the shadow cabinet like Michael Gove who have some understanding about the seriousness of the contemporary terrorist threat will be the losers as the shadow home secretary will become insufferable. He will have got his revenge for his leadership election loss and a payback on other issues like grammar schools where Davis has sniffed a sellout. But if he loses, can we expect a Tory u-turn on the 42 days issue?