Sinn Féin President Mary Lou McDonald has caused a stir for marching behind an Anti-England banner at the St Patrick’s Day parade in New York.

A photo showing McDonald standing behind the banner, which was tweeted by the party along with the caption: “No explanation needed”, has been widely – and rightly – criticised by political parties both in Northern Ireland and the Republic.

While I understand her sense of solidarity and the ever-present need to appeal to the Sinn Féin party base, especially the Irish-American one, the reality is that times have changed. Just because the banner has been in use since the Roosevelt era doesn’t mean it has a place in society today. It may have had relevance in the 1930s but I personally believe it’s time it was retired.

McDonald, choosing to have her photograph taken with the banner, is an issue of itself, but why did the party feel the need to use it as a photo opportunity and tweet about it for the world to see, with an accompanying provocative comment?

For me, the whole incident serves as an own goal by Sinn Féin and I just wish the party would do better. Like many, I’m weary of gutter politics.

Irish Deputy Leader, Simon Coveney was right to describe it as embarrassing. It was certainly in stark contrast to the confident and tolerant attitude displayed by Irish Prime Minister Leo Varadkar, who brought his boyfriend along to a meeting with US vice President, Mike Pence, who is anti-LGBTQ, during the St Patrick’s Day celebrations, and used the meeting to call out various forms of discrimination.

And even within her own party, whatever your view of Martin McGuinness, the incident is in stark contrast to the quality of progressive leadership he displayed when he met and shook hands with the Queen in 2012.

At the time, McGuinness said the handshake "was in a very pointed, deliberate and symbolic way offering the hand of friendship to unionists through the person of Queen Elizabeth for which many unionists have a deep affinity".

It was a huge gesture, and one that put Sinn Féin on a positive footing with many.

Sinn Féin are fully aware that progress is not made by intolerance and crass, political point-scoring.

As McGuinness showed, it comes from dialogue, and from openness and acceptance.

Assuming that Sinn Féin understand this, do we then have to assume that they simply don’t care about the effect of this level of intolerance on unionists?

I never envisaged a border poll on the reunification of Ireland in my working life and yet Brexit has acted as a catalyst for a conversation around the potential for a united Ireland in the very near future.

But how could we expect unionists to get behind a united Ireland and engage in meaningful dialogue when this is the message from Sinn Féin?

Language matters and promoting this kind of language only serves to alienate unionists. The party can continue to allege the banner simply refers to the British government’s role in Northern Ireland. But it is offensive to those who are English or who prefer to call themselves British, which is of course a key tenet of the Good Friday Agreement.

And contrary to what some people have suggested, the outrage felt by many is not merely around any implication that those identifying as English or British should get out of Ireland, it is the sense of division, the unwelcomeness and intolerance that such a sentiment suggests.

Sinn Féin are anti-imperialist and believe that the partition of Ireland is wrong. No one denies the party’s aspiration for a united Ireland, but this is the wrong way to go about it.

In fact, I would say they are doing more to harm the case for reunification with stunts like the one on St Patrick’s Day. If Ireland is to become united, the only way to do it successfully is by bringing unionists along and creating a wholly new, inclusive Ireland.

Anything less than this will be divisive and painful, perhaps even worse than the current Brexit mess.

None of the inhabitants of this island deserve that.