In the manner that the Speaker resigned his seat, it is not possible to move the writ during the summer vacation so it will be moved as normal in due course.
In other words: we have our reasons but we're not going to tell you what they are. The SNP tried to move the writ in parliament yesterday to ensure that one of Britain's poorest and most deprived constituencies didn't go without parliamentary representation until November. It may have been a stunt but the media is now saying the SNP is on the front foot and that Labour look pathetic. And they're right.