What a difference a week makes.

Last Friday in Grangemouth, there was a sense things were looking up. The threat of 800 job losses caused by the closure of the petrochemical plant had been lifted. Tears had turned to smiles. It looked as if everyone could move on at last.

Look at what has happened since.

There have been troubling reports all week about the behaviour of Unite and in particular of Stephen Deans, a local union official, chairman of Unite in Scotland and chairman of the Falkirk West Labour Party. The controversy does Labour no favours, as it has reignited the candidate selection row in Falkirk West.

Mr Deans helped recruit a large number of new local party members in a bid to have Unite's preferred candidate, Karie Murphy, selected to fight the Falkirk seat at the next election. He was subsequently suspended by Labour pending an inquiry, though was reinstated after key witnesses withdrew evidence.

This week, the row has come back to the fore, after emails were leaked suggesting ­officials from Unite plotted to undermine Labour's inquiry. It then emerged on a separate front that Mr Deans was being investigated by the information watchdog over possible data protection breaches. A day later a row erupted over the staging of union protests outside company officials' homes. All in all, for Unite and the local Labour party, it has been a bruising week and it is not over yet.

Falkirk West Labour Party are scheduled to hold a meeting on Sunday where there could be a motion of no confidence in Mr Deans's leadership.

Unsurprisingly, David Cameron has sought to capitalise on the controversy, calling upon Ed Miliband to hold an inquiry into Unite's actions.

Yet where is Johann Lamont in all of this?

Strictly speaking, she has been bypassed by internal Labour Party rules and structures. Authority for overseeing the proper selection of Westminster candidates rests not with the Scottish party but with UK Labour, which has put Falkirk West in "special measures".

That is a nonsense - Scottish Labour should have control over Westminster selections. Even within current arrangements, though, Ms Lamont might be expected to do more. She may not officially have a direct role in healing the sores in Falkirk West, but she is giving the impression publicly of having no influence either. Whatever might be happening behind the scenes, the impression remains that she is not taking action.

Alex Salmond has emerged from the Grangemouth affair rather better. He is in a very different position from Ms Lamont, of course, as a First Minister intervening to save an industrial complex rather than a party leader faced with a messy internal dispute, but where Mr Salmond has appeared industrious, Ms Lamont has not appeared at all. One can appreciate why she might wish to stay several constituencies away from this mess, but the longer she remains outside, the less in control she appears. The affair has exposed the limitations of the Scottish Labour leader's autonomy.