A 94-year-old D-Day veteran leaned forward and gave the Prime Minister a kiss on the cheek after meeting her in northern France.
Former Royal Marine Robert William Yaxley, 94, from Chelmsford in Essex, met Theresa May following a service at Bayeux Cemetery.
He was an 18-year-old commando in a landing craft that reached Sword Beach on D-Day 75 years ago.
"She came over and said 'pleased to meet you'," Mr Williams said.
"She said 'Thank you for what you have done'.
"I kissed her – why not? It is not everyone that can do that. I took her by the arms and gave her a kiss on the cheek.
"She said 'Ooh thank you'."
Mr Williams said that after reaching France, he made his way through to Germany "without a scratch".
The nonagenarian, who is a keen dancer, is on the Royal British Legion's cruise to mark the anniversary of D-Day.
Len Williams, 93, was an 18-year-old private with The Argyll and Sutherland Highlanders and landed on Gold Beach a few days after June 6.
He said his meeting with Mrs May, who was accompanied by husband Philip, "couldn't have been more perfect".
John McOwan, 98, from Peebles in the Scottish Borders, was a sergeant with the Royal Electrical Mechanical Engineers on D-Day.
He landed on Sword Beach four days after June 6.
"The Prime Minister said she was very pleased to meet me," Mr McOwan said.
"I said that I admire her very much and she smiled.
"This whole trip has been mind boggling. I shook hands with President Macron in Portsmouth, as well as Sheridan Smith.
"The service was very emotional. The tears were running down my face because it was so touching."
He brought a cross for school friend Johnny Lowry, an RAF pilot killed during the Second World War.
Mrs May also spoke to John Groves, 93, who was a guardsman with the Scots Guards and landed on Gold Beach days after D-Day.
She told him: "It has been a great pleasure to be able to see so many veterans here and be able to thank you for what you did."