But how do you replace a song, whose chorus promises "though cowards flinch and traitors sneer/we'll keep the red flag flying here"? Written by Jim Connell, a Victorian Catholic Irishman who filled it full of blood sacrifice, and sung to the tune, "Oh Christmas tree, oh Christmas tree/How lovely are your branches," "The Red Flag" combines populism with fundamentalism.
Parties are often not adept at changing their political tune. When Labour adopted Queen's "We are the champions" for its 1991 conference, it looked yobbish. And the Liberal Democrats, accompanied this week in Brighton by "Search for the hero inside yourself", sound as though they are selling not policies but Peugeots.
So what could Labour do, if it decided to lower "The Red Flag"? One simple alternative would be a famous bastardised version of the hymn, striking an aspirational new Labour pose, which begins: "The working class can kiss my ass/ I've got the foreman's job at last". Another rendering whose time has come opens: "The cloth cap and the working class/As images are dated/ For we are Labour's avant garde/ And we are educated."
But perhaps a new tune is needed. In Labour circles, there's much support for William Blake's "Jerusalem", a rousing hymn about creating God's own city. But it's utterly English - bound to annoy the Scots. Worse, the Tories (who don't seem to understand Blake's rallying call to social justice) already sing it themselves. There is also support for, "I vow to thee my country", but the tune sounds too much like an advert for full-cream butter.
Mr Blair needs to think afresh. Yesterday, Tony Banks MP, after a full and errorless rendition of "The Red Flag" down the phone from Strasbourg, suggested: "What about `The sun has got his hat on, hip, hip, hooray' or `Jesus wants me for a sunbeam'? They would appeal to the broadest section of people. That's what the Labour party's for these days, isn't it?"
"It's my party and I'll cry if I want to", the Sixties classic, also wins support among disenchanted Labour figures. As does "Money Makes the World Go Round", "Things Can Only Get Better" and, in anticipation of a post-election love-in with the Liberal Democrats, "Tie a yellow ribbon round the old oak tree".
A compromise that might please many would be the music hall number: "It's the rich wot gets the pleasure/ It's the poor wot gets the blame/It's the same the whole world over/ Ain't it all a bloody shame." But this would surely meet the same objections as "The Red Flag".
No, the Labour leader will have to get radical to strike a truly Thatcherite pose and win over wavering Tories. Noel Coward should be his muse. How about the 1938 song: "The stately homes of England/We proudly represent"?