Mr Cameron today welcomed President Michael D Higgins to residence at Number 10 Downing Street, adding that both countries have become "deep friends".
Mr Higgins told the Prime Minister that the relationship between Ireland and Britain is evident in our strong trade and economic links.
Both politicians referred to the issue of the Peace Process and the continued effort regarding the resolving of issues in the North.
Speaking publicly for the first time during Mr Higgins's State visit to the UK, Mr Cameron said Anglo-Irish relations are now on a "ever increasing gradient".
"I am really excited by the things that we are now doing together, two countries and two governments. I am excited by some of the new projects that we are talking about," Mr Cameron said.
"But we must, as you said last night and Her Majesty said last night, keep on with the work of reconciliation, including in Northern Ireland. It is wonderful the visit that you are making, it builds on Her Majesty's excellent and remarkable visit of three years ago," he added.
Mr Higgins said that he believes that the short distance between Ireland and Britain has "sometimes stopped us from seeing the richness in each other".
He added: "But I hope that the visit will enable great opportunities for the deepening of the peace process that we have, that requires our continuing vigilance. As head of state I am so pleased to say thank you as well for the incredible reception that I have received.
"I had an opportunity of expressing to Her Majesty last night my gratitude for the reception for the Irish community in anticipation of my visit. I am so pleased to be here, Prime Minister and I wish you well as I wish the head of the Irish government wellin your co-operation advancing on these issues."