For Tony Blair it will be a birthday surprise, surprise but BBC viewers are more likely to be in for a lorra, lorra laffs when Cilla Black performs a Marilyn Monroe-style rendition of Happy Birthday for a BBC2 tribute to the prime minister.
The veteran TV presenter and one-time pop star is following last year's infamous turn at the Royal Variety Performance, when she wore a neon basque and stockings, with a husky voiced impersonation of one of the most iconic moments in Monroe's career.
Captured on film serenading lover President John F Kennedy at his birthday party in Madison Square Garden in 1962, Monroe's sexually charged delivery of the song has become one of the most memorable and mimicked birthday party tricks.
Black's performance, recorded in secret at a London hotel two weeks ago, is part of an hour-long programme entitled Happy Birthday Mr Prime Minister, to be shown on BBC2 on May 4, two days before Mr Blair's 50th birthday.
A spokeswoman said she had not gone quite as far as dressing up as Monroe but does deliver the chorus in a similarly "breathy voice".
In what the BBC is describing as a light-hearted look at the prime minister's achievements, Black is also interviewed about Mr Blair.
When the former ITN political editor, John Sergeant, asks her if she fancies the prime minister, Black replies: "He's too young for a start. Well, maybe he isn't now he's 50 - I could easily spend an evening with him."
The show will be broadcast just days after Black's final appearance on the long-running ITV game show Blind Date.
Her switch to the BBC will be seen as a snub to her erstwhile employer, with whom she had a public falling out.
Black made the tabloid front pages last year with her Royal Variety Performance routine. She sang You've Gotta Have a Gimmick, a song from 1962 musical Gypsy in which an older stripper advises an aspiring one.
Black ended her performance by thrusting her bottom in the air - revealing a twinkling neon heart.
Happy Birthday Mr Prime Minister will be hosted by Sergeant, who visited Mr Blair's Sedgefield constituency to put together a political profile of the politician.
The show will include interviews with Neil Kinnock, Roy Hattersley, Peter Mandelson, Mo Mowlam and the deputy prime minister, John Prescott, as well as a guest appearance from former US president Bill Clinton.
Gordon Brown does not make an appearance although the BBC could not say whether the chancellor was invited to participate.
The BBC said the programme would try to ease Mr Blair's worries about turning 50 by seeking advice from TV chef Gary Rhodes and wine aficionado Oz Clarke on creating the perfect birthday party.
