His comments come as it emerged British Prime Minister Theresa May has written a letter giving the formal backing of the British Government to the Irish bid.

She and her staff wore Ireland 2023 pins during the meeting with Taoiseach Leo Varadkar in Downing Street.

Mr Varadkar, speaking after the bid, said he was grateful for the support.

“She has written to World Rugby supporting the bid and assuring them that the United Kingdom Government, because obviously Northern Ireland is part of the United Kingdom, that the UK Government is behind it too. I’m very grateful for the fact that she’s done that,” he said.

Mr Varadkar said that hosting the competition could result in a net boost of about €750 million to the Irish economy. He was responding to concerns about the need of the Irish Government to underwrite the bid.

“We see this as a net investment in the Irish economy, so any investment will be recovered in terms of the additional revenues that would be brought in with the hosting of a tournament – we estimate a boost of about €750million,” he said.

Mr Ross too expressed confidence the guarantee given by the Government is not a risk to the taxpayer, saying it is “the safest of bets”.“These are projections, they have been absolutely scrupulously and forensically examined, they look extraordinarily good. Past experience is that the British rugby world cup filled all the stadiums, we expect to fill them many, many times over,” he said.

“There is some risk attached, there is with every commercial venture but we’re very sure we’re heading from something that will not just be an immediate boost to the economy but will have a permanent effect on the economy because 450,000 will come and some of them will come back again. It will send the message that Ireland is modern nation that competes with the best and can put on an event of this type,” Mr Ross added.

Mr Ross and Mr Varadkar said that Brexit should not pose any real difficulty in terms of the bid.

“Brexit is a red herring which I think is being somewhat mischievously produced as an issue or something that will be an obstruction. We have a united approach from Ireland approach to this from North and South and I don’t think Brexit will make any difference at all,” Mr Ross said.

“There were a number of questions and understandably one of them was about Brexit – will people still be able to travel freely between Ireland and Northern Ireland after Brexit and I was able to reassure people that while there are a lot of uncertainties about Brexit, one thing we are certain about is retaining the common travel area, it’s one thing that London, Dublin, Belfast and Brussels all want and I’m confident that won’t be an issue,” Mr Varadkar said.

Ireland's two rivals – France and South Africa – also presented their bids to the selection committee in a Kensington Hotel, but Mr Varadkar was the only political leader present.

“I think people will get behind this, the French have said that this will cost the taxpayer nothing, well we take the view that because of the influx of people and revenue that we’ll actually gain from this financially, that this is actually a good investment in our economy, as well as in our infrastructure which will have to be improved, and finally for sport,” said Mr Varadkar.

“It is fully-backed by the Government, I’m here in person, the only head of Government to be here in person supporting the bid.

“We have legislation brought through by Minister Ross through our parliament showing that we’re very much behind this and in addition to that we have a fan base around the world and a huge Irish diaspora that are going to get behind this.”