Daily Announcement - Labour MP to stand down

In what is becoming a daily announcement on this blog, I have to let you know that yes, once again a Labour MP is standing down at the election, this time it is the turn of Tommy McAvoy, the MP for Rutherglen and Hamilton West.

Tommy McAvoy has decided after to stand down at the age of 66 after 23 years in Westminster.

Jim Murphy, the Secretary of State for Scotland (a Labour MP who isn't standing down) said:

Tommy is not just an MP - he is an institution. He is the longest serving government whip of all time.

Prime Minister Gordon Brown described the 66-year-old, who has been a whip for 13 years, as a "titan" of politics.

Again though, I ask the question, why do these MPs decide now, just a matter of weeks until the general election to stand down?

What is going on within the Labour Party?  Does anyone actually know or understand all of these last minute resignations?