Irish President Michael D Higgins visiting London
Ireland's president, Michael D Higgins, is making his first visit to London since taking office.
It is not a state visit and Mr Higgins will not be meeting any members of the Royal Family.
However, an official state visit to Britain - the first since Ireland became a republic - is expected within the next three years.
Mr Higgins recently succeeded President Mary McAleese, who last year hosted the Queen's first visit to Ireland.
On his two-day visit to London, he will be attending a function at the Irish Centre in Camden.
The president will make a speech at the London School of Economics entitled 'Of public intellectuals, universities and a democratic crisis'.
He will be shown around the Olympic stadium by Lord Coe, the London 2012 chairman.
A great lover of the arts, Mr Higgins will also be attending a production of Juno and the Paycock at the Lyttelton Theatre.
In the wake of the Queen's historic visit to Dublin last year, an official return visit is expected. However, the usual protocol is that an invitation is not issued immediately.
Instead, a period of up to three years could pass before Mr Higgins is invited to take part in a UK state visit.
This year is a busy one for the Queen with the Diamond Jubilee and the London Olympics.
In a recent interview with the Irish state broadcaster, RTE, Prime Minister David Cameron said that he would like to see an Irish state visit take place during his time in Downing Street.
President Higgins studied for three years at Manchester University and has strong links with England.
The amount of Irish people across the Irish Sea in Britain was mentioned in a recent speech by Prince Charles.
He said: "I hadn't appreciated quite how many Irish live in this country, some say as many as six million once you've started taking into account second and third generations.
"Nor had I appreciated, regrettably in my ignorance, that there was such an enormous amount of trade and business that went on.
"In fact three times the amount of business is done between the UK and Ireland than is done with China."
The Queen's four-day visit to Ireland last May was her first, but there are some suggestions that it will not be her last.