But he is ready to wait another ten or 15 years for another referendum if that’s how long it takes to get a majority for independence.
The SNP-supporting musician believes social inequality will only grow in the short term, fuelling a split.
He said: “It’s now become obvious that it’s going to be difficult to keep the present Union going.
“My argument would be that it’s dead, that it died with the majority victory for the SNP [at the Scottish Parliament elections] in 2011 and then the vote on independence.
“It would appear to me there’s only two choices now, federalism or Scottish independence. Whether [David] Cameron faces up to that or not – I suspect he won’t – I think the European thing is going to be by far the bigger priority for him.
“The worst cuts we’ll see will be over the next two years so the political choice is going to become very stark.
“People are very electioned-out in Scotland. The SNP’s quadrupled its size but I think they’ve got to be very careful.
“I speak as someone who wants Scotland to be independent and who thinks that Scotland will inevitably get some sort of federal deal at some point but would prefer to see all sovereignty here and then we can do deals on what we share with England, defence and whatever.
“The only reason to hold another referendum is if you think you can win it, and if you can’t there’s no point. If it means ten or 15 years, that’s the way it goes.”
Charlie and twin Craig – son-in-law of late Independent Lothian MSP Margo MacDonald – have just released their tenth album, Let’s Hear It For The Dogs, and are due to appear at a series of festivals across the UK this summer, including T in the Park and Belladrum.
Nearly three decades into their career, Charlie believes the twins still have things to say.
He said: “For us it’s important to keep producing new songs, whether or not they’re successful. You want something new to give to the fans and something new to play on stage.”