Picking Ireland's religious capital Armagh as a venue for their latest visit may have been an attempt by the British and Irish prime ministers to stress the importance of north-south co-operation.
But whether they knew it or not, Tony Blair and Bertie Ahern's diary secretaries fixed on a date which has very different connotations.
On 6 April, it is the 80th birthday of the leader famed for calling the Pope the "anti-Christ" and vowing that he would "never, never, never" bend to the will of London and Dublin.
DUP leader Ian Paisley pictured outside Stormont in 1969
Far from being a fading presence on the political scene, DUP leader Ian Paisley is now more central then ever.
The two prime ministers may send him birthday wishes, but only he can give them the present they want - the return of power sharing at Stormont.
Sitting down for a cup of tea with his wife Eileen, dog Bridie and cats Byron and Shelley at the family home in east Belfast, the DUP leader - who is still holding out against entering an executive with Sinn Fein - shows no sign of giving the governments what they want.
Ask him if by his 81st birthday, he sees himself as Northern Ireland's First Minister and he tells you it could happen or it could not.
"I am not running around saying 'Make me first minister'. If I wanted to be made first minister I could make myself first minister by selling my country out.
"But I'll be selling nobody. I can't be bought, I can't be borrowed and I'm not going to bend because the people have given me a very strong mandate, and God forbid that I should fail them."
Back in 2004 at the time of the Leeds Castle talks, Ian Paisley was obviously in poor health.
Ian Paisley addressing a rally in Ballymena in 1981
He did not take kindly to the press interest in his condition and still won't reveal any precise medical details.
But he now looks fit and says his doctors have declared him "a whole man... I have energy, plenty of thinking capacity, a good memory and I'm doing alright."
Whilst his supporters view him as Ulster's greatest protector, Ian Paisley's detractors blame him for stirring up division.
At the time of the referendum on the Good Friday Agreement, he was written off as a political dinosaur and some loyalists portray him as a "Grand Old Duke of York" figure who marched young men up to the top of a hill before abandoning them when they became drawn into political violence.
The DUP leader insists that whenever groups like the Ulster Resistance turned to violence, he stuck to his democratic principles by immediately distancing himself from them.
He says he has been written off many times only to come bouncing back.
As far as his critics are concerned, he laughs them off, reminding them of his success at the ballot box in supplanting the Ulster Unionists as the biggest party.
The DUP leader and his wife Eileen are obviously a happy couple, parents to five children and grandparents to ten.
Ask Eileen to say something bad about Ian and she will only tell you that he works too much.
Then on second thoughts she adds that he's not much cop at making soup.
They share the same political and religious convictions. He says he has relied heavily on Eileen in giving him the strength to lead both his party and his Free Presbyterian church.
Although in recent years she has concentrated on her family, Eileen was an elected member of Belfast City Council in the 1960s before her husband held office.
Bertie Ahern and Tony Blair were unveiling their latest blueprint
Now he is making her one of the DUP's three new peers in the House of Lords, although the announcement has been held up by the controversy over the Labour "loans for peerages" allegations.
In London, the notion of a party leader putting his wife in the House of Lords would no doubt raise a similar ruckus.
But in the DUP - the closest thing Northern Ireland has to a hereditary monarchy - it seems par for the course.
On 6 April, Tony and Bertie no doubt hope that Ian will give their latest blueprint the thumbs up.
But the DUP leader says that on his birthday he will be concentrating on the junior Paisleys - his grandchildren who range between 19 years and four months.
"I'll be the biggest child at the party. They'll be on top of me. They'll be rolling under these seats. They'll be climbing on my back. They'll be slapping me in the face. They'll be saying no to some of my requests. And I shall enjoy it thoroughly," he said.
Only after the celebrations are over will his thoughts turn to his next move in the long-running Stormont game.