When will the by-elections be held

I have discussed before when the by-election in Michael Martin's former seat could be called to mitigate damage to Labour.  The matter pops up again this morning:

Gordon Brown is under pressure to move the writ for the Norwich North by-election this week, or face the risk of losing the seat in the autumn, so reopening the arguments about his leadership.

He has delayed partly because he wants to hold the Norwich vote at the same time as the by-election in Glasgow North East, being held due to the retirement of the Speaker Michael Martin.

As also noted:

….if the by-election is not held on July 16 or July 23, with the writ moved almost immediately, it cannot take place until after parliament returns in October.

If the by-elections are not called for July, this possibly gives a clue as to whether Brown is considering an October election.  If he is, but has not finally decided, there is little point in moving the writs now.   Only if he has ruled out an October election will the by-elections be held at the end of July, after the Commons has adjourned for the Summer recess.