Sam McBride: Rather than being apathetic, Villiers was implementing Cameron's central policy

Ms Villiers’ somewhat shy personality and the fact that with devolution she inherited a radically shrunken role meant that unless there was a political crisis she often seemed like a bystander to political events.

That led to the frequent suggestion from some politicians and political commentators that she looked like she didn’t want to be in the job.

While the instinctively cautious Ms Villiers made for far less flamboyant copy than her exuberant and outspoken predecessor Owen Paterson, the truth is that Ms Villiers was largely following David Cameron’s central policy towards Northern Ireland.

Much of the criticism of Ms Villiers is similar to that of Mr Cameron – that they were disengaged from Northern Ireland.

But while it is easy to interpret that as apathy, it was actually the outworking of Mr Cameron’s policy towards Northern Ireland, which was founded on a unionist belief that the Province was an integral part of the UK, and that there was no point in having devolution if the national Government was to keep butting in.

Mr Cameron’s engagement with Northern Ireland was so distinct from that of his predecessors that many people on this side of the Irish Sea still struggle to see it as anything other than apathy – if not outright disregard – for the Province.

Tony Blair and Gordon Brown regularly welcomed Northern Ireland’s political leaders to Downing Street to discuss their latest crisis but from the moment he entered Downing Street Mr Cameron made clear that he would adopt a radical change to the previous approach to Stormont’s leaders.

Ms Villiers implemented that policy by largely leaving the DUP and Sinn Fein to get on with day to day government and determinedly reminding the Executive of her intention to do so – even at the points whenever Stormont found itself in the midst of a self-inflicted crises, such as the budgetary mess after Sinn Fein refused to implement welfare reform.

Her tenure was also shaped by the fact that she and her predecessor Owen Paterson had less responsibilities than any previous holder of the post.

The restoration of Stormont in 2007 saw the NIO shorn of its obligation to oversee day to day government in areas such as health and education, while the devolution of policing and justice in 2010 removed some of the biggest remaining areas of executive power.

That lack of onerous responsibility means that the post holder can fashion the job into almost whatever they want it to be.

A criticism of Ms Villiers would be that she did not really turn the role into anything particularly memorable.

Unlike Mr Paterson who embraced a sort of roving ambassadorial role for Northern Ireland, seeing himself as a champion of the Province both nationally and globally, Ms Villiers was a quieter more managerial figure. She was though much less abrasive than her sometimes mischievously robust predecessor.

Over time, Ms Villiers developed warmer relationships with local unionist leaders than with Sinn Fein and the SDLP, partly because she and unionists found themselves on the same side of several major arguments, from welfare reform to addressing the legacy of the Troubles.

But although – and perhaps partly because – she was widely perceived as being dull, the lawyer and former MEP rarely made major mistakes.

That explained her surprisingly long tenure in office – she was the third longest serving secretary of state and just 11 days short of the second longest serving, Tom King.

In person, Ms Villiers was impeccably polite. She appeared to be fairly straight in her political dealings and certainly had none of the Machiavellian tendencies of some previous holders of the post such as Peter Hain and Shaun Woodward.

In the end, the biggest problem which she has left her successor is identical to that which the man who appointed her has left for Theresa May: how to implement Brexit.