Brandon Lewis has been named new Secretary of State for Northern Ireland by Prime Minister Boris Johnson.

Mr Lewis was previously Minister of State for Security and Deputy for EU Exit and No Deal Preparation.

I am honoured to have been appointed Secretary of State for Northern Ireland by the Prime Minister. This is an exciting time for Northern Ireland & I follow fantastic colleagues as predecessors, whose work I hope we can continue to build on. — Brandon Lewis MP (@BrandonLewis) February 13, 2020

His appointment comes after Julian Smith became the first casualty of Mr Johnson's government reshuffle after being unceremoniously dumped from the Northern Ireland Office.

His departure comes just weeks after brokering the deal which restored the power-sharing administration in Stormont.

Mr Smith said it had been "the biggest privilege" to serve the people of Northern Ireland and he was "extremely grateful" to have been given the chance to serve "this amazing part of our country".

"The warmth & support from people across NI has been incredible," he said on Twitter. "Thank you so much."

Serving the people of Northern Ireland has been the biggest privilege. I am extremely grateful to @BorisJohnson for giving me the chance to serve this amazing part of our country. The warmth & support from people across NI has been incredible. Thank you so much. — Julian Smith MP (@JulianSmithUK) February 13, 2020

Mr Smith was called in to see the prime minister in his Commons office as the reshuffle began.

Taoiseach Leo Varadkar said on Twitter that Mr Smith is one of the finest British politicians.

In 8 months as Secretary of State, Julian you helped to restore powersharing in Stormont, secured an agreement with us to avoid a hard border, plus marriage equality. You are one of Britain's finest politicians of our time. Thank you https://t.co/sm2QHFvUtu — Leo Varadkar (@LeoVaradkar) February 13, 2020

Tánaiste Simon Coveney also commented on Twitter that Mr Smith was an effective Secretary of State.

U have been such an effective SOS for NI at a time of real challenge & risk. Without your leadership I don't believe NI would have a Govt today. Thank you @JulianSmithUK for your trust, friendship and courage; UK & #Ireland can look to future with more confidence because of it. — Simon Coveney (@simoncoveney) February 13, 2020

Later, speaking on RTÉ's Today with Sean O'Rourke, Mr Coveney said many people in Northern Ireland - from all backgrounds - will be bewildered by the decision to sack Mr Smith.

Mr Coveney said Mr Smith achieved an extraordinary amount during his six months in the job.

Sinn Féin leader Mary Lou McDonald said that her party had had very intensive contact with Mr Smith during the recent re-establishment of the power-sharing government. She said it helps if there is some level of continuity in terms of who you are dealing with.

There are many outstanding issues regarding power-sharing, she said, "not least the issue of legacy where the British establishment has dragged its feet".

"We had commitments from Julian Smith that he would move swiftly so we are now concerned that it's not just the sacking, but that it is the British state again rowing back on dealing with issues of legacy."

She said there are families who have suffered and who suffer still and who have waited in many cases for decades for answers.

"We will wait to see who his replacement is and of course will be looking to meet with them as a matter of urgency."