Iron Lady Margaret Thatcher revealed her Irish roots at a London dinner to celebrate Britain’s victory in the Falklands war.

A new documentary for Irish national broadcaster RTE claims that Thatcher admitted to a great-great Irish grandmother.

The remarks stunned British diplomat Sir David Goodall who has revealed the 1982 conversation to the Irish broadcaster.

Goodall was sat with Thatcher at the private dinner in Downing Street when she revealed that her great, great grandmother was an O’Sullivan from Ireland.

The Sunday Independent reports that the dinner-table conversation led the so-called ‘Iron Lady’ to make a commitment ‘to do something on Ireland’.

The comments are contained in new documentary ‘Thatcher: Ireland And The Iron Lady’ which examines her relationship with Prime Minister Jack Lynch, Charles Haughey and Garret FitzGerald.

It also examines behind-the-scenes looks at key events including the IRA hunger strikes and the signing of the Anglo-Irish Agreement in 1985.

Goodall recalls the conversation he had with Thatcher at a dinner held to celebrate the British victory in the Falklands War.

He claimed: “I said in the course of this conversation, ‘Relations between Ireland and Britain are complicated by the fact that so many of us in this country are of Irish descent and although they don’t like to say so, so many people on the island of Ireland are actually of British descent’.

“Mrs Thatcher listened to that and then she said, ‘I am completely English’. So I said, ‘Well, I’m not. I mean, one of my grandfathers was born in Ireland and there are hundreds of thousands of people in this country like me’.

“And she said, ‘H’mm, now you mention it, my great, great grandmother was O’Sullivan, so perhaps I’m one-16th Irish’.

“At the end of this conversation, she said reflectively, ‘H’mm, if we get back again, I think I’d like to do something about Ireland’.”