After months of internal squabbling and public nastiness, the Labour Party finally appears to have remembered that its primary function is to provide proper opposition to the Government, not itself. To mirror the 170 days till the end of March – the deadline set by the Prime Minister for triggering Article 50 and the official start of Britain’s long withdrawal from the EU – Labour released 170 questions about the Government’s approach to Brexit. It was more than a neat gimmick: the questions had substance and put the Conservatives on the back foot. The appointment of Keir Starmer to the shadow Brexit brief last week may prove one of Jeremy Corbyn’s more sensible reshuffle decisions.

By releasing the questions in advance of an opposition day debate, Labour suddenly looked like it was the party making the running. It also gave Jeremy Corbyn a basis from which to attack Theresa May during Prime Minister’s Questions, and it was a chance he took largely to good effect. The Prime Minister, by contrast, was defensive and relied on the kind of broad-brush answers that have too often characterised the Government’s efforts to explain the Brexit it envisages.

For all that PMQs is in many ways a faintly absurd piece of theatre, it provides the public with an important window into the workings of Parliament. Just as significantly, it can change the mood of political parties as they see their leader gain or lose the upper hand over their rivals. The difficulties encountered by Jeremy Corbyn during the first nine months of his leadership were magnified by his poor performances at PMQs, when his earnest, rather dour and sometimes shambolic efforts were shown up by David Cameron’s ready answers and witty put-downs.

Theresa May is not in the same class as her predecessor and all of a sudden Corbyn looks less court jester and more assured prosecutor. His questioning is, for the most part, more pointed; he appears more at ease with the format, perhaps a consequence of being more secure in his position following his re-election as leader.

All of this is important for anybody who believes in parliamentary democracy. The truth is that governments function best when they are held to account by an effective opposition: Labour has not provided it since before the last election. With the Liberal Democrats saying good things but without the numbers to muster real clout, much has been left to the SNP in the last year. But a party whose primary interests lie in Scotland (and are invested in the country’s future independence) can only represent the British electorate so far. The glimmer of a Labour revival should be a cause for great cheer, even if anxieties remain about Jeremy Corbyn’s ability to make the party a true election force.

Indeed, just as it has been frequently suggested that Labour’s disunity could give Theresa May’s Government a free hand, so potential Tory divisions over Brexit could provide Labour with a common focus around which to regroup. The Prime Minister’s arrogance at the Conservative conference, where she sought the approval of those who voted to leave the EU at the explicit expense of those who did not, showed surprisingly poor judgement. To back that up with rhetoric that was at turns anti-immigrant and anti-business simply raised the heckles of people who she needs on her side.