This time two years ago, I took part in the first ever United Kingdom televised leaders' debates ahead of the General Election. With seven leaders from across the political spectrum representing an array of views, it seemed as if the UK was finally entering an age of genuine multi-party politics.

Fast forward to 2017 and the fallout of the UK's decision to leave the European Union, and the picture is different. The EU referendum campaign was the ugliest, most divisive I can recall. For all the Tory government's empty rhetoric on uniting "the country" after June 23 last year, their record so far shows a determination to do the exact opposite.

Last night I appeared on the Question Time panel from Wigan. Sat next to me was the Secretary of State for Exiting the European Union, David Davis. From the outset, his tone was antagonistic and his answers evasive.

When I challenged him over the Tories' appalling legacy of foodbanks and homelessness, the Secretary of State adopted the very traits which have become symptomatic of this scrutiny-shy administration.

Day in day out, government ministers are getting away with swapping meaningful responses for slogans and soundbites. Often, as we saw last night, they will resort to an intimidating or divisive tone to deflect from their failures. There should be no place for this behaviour in our politics.

More concerning still is the fact that the Prime Minister herself has also fallen foul of this malaise. In recent weeks, we have seen Theresa May refuse to take part in the televised leaders' debates, denying people the opportunity to see her challenged on the issues which matter to them in front of an audience of millions. That refusal has given the perfect, convenient excuse for the Labour opposition leader to threaten to do the same.

Only a few days ago, the Prime Minister's astonishing accusations that EU leaders were seeking to influence the outcome of the upcoming UK Election drew warranted criticism. Adopting such a belligerent tone is not worthy of her office and is sure to weaken the UK's hand before the negotiations even begin in earnest.

Plaid Cymru has always acted as a robust and effective opposition whenever placed to do so – in Westminster and in the National Assembly and in local authorities. We believe that the Prime Minister and her government should be held to account and challenged in the strongest possible terms whenever they fail to defend their record or seek to lower the tone of public debate. People deserve better than a government whose agenda is dominated by deflection and disrespect.

In a few weeks' time, the televised leaders' debates will be upon us once again as the UK prepares to go to the polls. I will be taking part, regardless of the Prime Minister and Leader of the Opposition's refusal, and look forward to sharing our ambitious programme for protecting Wales's economy and public services as we prepare to leave the EU.

With a Tory Prime Minister in Westminster more interested in dodging the media than dealing with the issues affecting people who are struggling, and a weak and divided Labour party offering pitiful resistance, it is left to Plaid Cymru to defend Wales.

If this government is to make a success of the UK's departure from the European Union, it must choose diplomacy over dogma. We must continue to hold this Tory administration to account and demand that our nation is treated with the respect so absent from UK politics at present.

Leanne Wood is Leader of Plaid Cymru – The Party of Wales