There are some MPs, no matter which party they belong to, who command respect from their opponents. Andrew MacKinlay is one of those MPs. But he has decided tonight to tell his Constituency Labour Party in Thurrock that he will not be a candidate at the next election. It's got nothing to do with expenses, but all to do with the fact that he is physically exhausted and, I think, very disillusioned with the way Parliament is heading.

I have known Andrew since 1991. We met when we were both monitoring the progress of the Ports Bill through its committee stage. He was working for a trade union and I was advising port authorities. I have immense respect for him and what he has achieved in Parliament since he was first elected in 1992. He has been a courageous, independent voice, often taking on vested interested. But throughout his 17 years he has developed into a fine parliamentarian. The fact that he has so clearly fallen out of love with parliament should set off a few alarms.

I spoke to Andrew at length yesterday about his decision. He says he is "physically and mentally burned out" and that ideally he'd like a sabbatical, but recognises that this is just not possible in politics, commenting: "An MP has no deputy or substitute. In many other jobs it is possible to take a sabbatical. This is impossible for an MP". He describes the job as "unrelenting" and has come to the conclusion that "something has to give". He can't remember having a weekend off and says he is on duty 7 days a week, 365 days a year. He says this not to plead for sympathy but because he has reached a stage where he is worried for his health if he continues in this way. "I need to recharge my batteries. Life is short," he said.

Although he made the decision to quit some months ago, the debate I wrote about HERE on the Gary McKinnon case appears to have served to strengthen his resolve. I get the feeling he has grown increasingly disillusioned with the direction in which parliament is headed and has become frustrated at the inability of his fellow MPs to hold the executive properly to account.

But it is the exhaustion side of this decision that should give us all pause for thought. The job has been his life, and he is not untypical in that. Whenever Mackinlay has taken an annual holiday (which since 2000 he has taken every year within the UK) he has, each day, had his official post pouched sent on to him. But that won't be happening this year. To his wife's frustration he has, in recent years, frequently interrupted many a holiday by agreeing to pop in to a nearby television studio to do "down the line" interviews the request of some television journalist in London. She has tried in vain to restrict his "all too ready availability".

The measure of an MP’s success can be high an ever increasing case load. If they are any good they attract work like a miracle worker. This is especially true in marginal seats like Thurrock, where an MP always has to be on his toes. In turn, good MPs have an ever increasing rate of invitations in the constituency... and indeed elsewhere.

In short, if you are in a marginal seat, it's difficult to say no. And that can lead to exhaustion and burnout. Some people find it very difficult to achieve a proper work-life balance and MPs are no exception.

MacKinlay is certainly a maverick. He has a slightly eccentric ritual of a few days into every parliamentary recess going up to what he alleges is are largely empty offices/ press gallery and muttering "Where is every body? This is place looks like the bloody Marie Celeste". Indeed, I am told he did that this afternoon after having received the Daily Telegraph's missive on MPs' holidays. Not a single soul was he left them a message saying: "I came to see you - but you were not here...Andrew Mackinlay. P.S. I am working".

I want to see more MPs like Andrew MacKinlay - true parliamentarians with an independent streak. I think there will be MPs from all parties who are as sad as I am at the news.