temper_tantrum
The beauty of the ride
Depends what you mean by "politically unnecessary". It smells bad. The only solid reason I can see for a whip was if Militwat's coterie got whiff of a "for" vote beforehand, which would have reflected badly on the leadership. In that case, whipping the vote would have made good sense from the POV of the leadership, although whipping is a weapon of diminishing returns, as John Major found out.
I mean that (as far as I know) there was no likelihood of the ConDems failing to get it through. So it was politically unnecessary for Labour to take a position (we'll leave moral necessity out of it, as they seem to).
Therefore it's another example of Labour needlessly shooting themselves in the foot and expending some of their tiny remaining reserves of political capital. Fools.