Sinn Fein's Martin McGuinness is to make a keynote speech on British/Irish relations in London on Thursday evening.
The former IRA commander turned Northern Ireland Deputy First Minister will address a party event in Westminster following yesterday's historic meeting with the Queen during her two-day visit to Northern Ireland.
Their handshake has been hailed a watershed moment in the region's peace process and a potent symbol of reconciliation following years of violence when the IRA and British forces appeared implacable foes.
The encounter at a theatre in south Belfast would have been unthinkable a decade ago but the success of the peace process and the Queen's acclaimed visit to the Republic of Ireland last year changed minds.
Her conciliatory words in Dublin won over many critics of the monarchy and paved the way for yesterday's meeting.
The handshake was public and Mr McGuinness told the Queen in parting words of Irish: "Goodbye and God's speed."
The Mid-Ulster MP is said to have spoken to the Queen, whose cousin Lord Mountbatten was killed by the IRA in 1979, of the significance of her visit and of the need for it to be built upon in the time ahead.
Tonight's event will be attended by Sinn Fein MPs Michelle Gildernew, Pat Doherty, Conor Murphy and Paul Maskey. Sinn Fein TD for Dublin South Central, Aengus O Snodaigh, will also be in attendance.