THE significant constitutional shift of giving 1.5 million 16 and 17-year-olds across the UK the vote edged closer yesterday after Downing Street made clear that the option of allowing 126,000 Scottish teenagers to participate in the 2014 independence referendum was "on the table".

Up until now, David Cameron has set his face against Alex Salmond's call to allow Scottish teenagers to take part in the poll on the future of Scotland, making clear that it would adhere to the current franchise – only those over 18 would be allowed to vote.

In February, Michael Moore, the Scottish Secretary, insisted 16 and 17-year-olds would not be given the vote, saying: "So far, we have not yet heard a convincing argument that says you should change the basis of the franchise on this one-off referendum.

"The fairest basis is to use the franchise that elected the very parliament that gave the First Minister his mandate to have a referendum."

This position was adopted despite the fact that the Liberal Democrats as a party support extending the franchise, as does Labour.

As recently as April, the UK Government, following its consultation on the independence referendum, made clear 16 and 17-year-olds would not be allowed to vote in the independence poll; the consultation showed 44% backed giving youngsters the vote while 47% were opposed.

However, yesterday No 10 made clear the Prime Minister had softened the Coalition's line. His spokesman said: "These are all issues for discussion."

Coalition sources said the UK Government's apparent shift was meant to show that it was being reasonable and willing to compromise in the hope that the First Minister would abandon any idea of proposing a second question on the independence referendum ballot paper.

Mr Cameron's spokesman argued that allowing 16 and 17-year-olds the vote in the Scottish poll would not set a precedent. "You are doing two different things," he said. "One is a referendum about the independence of a nation, which is irreversible. The other is the election that decides the government for the next four to five years. It is quite a big decision."

However, campaigners for lowering the voting age made clear a precedent would indeed be set.

Katie Ghose, chief executive of the Electoral Reform Society, which supports votes for 16 and 17-year-olds, told The Herald: "The argument for votes at 16 should be advanced on its own merits, not as part of some deal over the referendum. The Government has got to stop doing deals on important constitutional questions."

Grant Costello, chairman of the Scottish Youth Parliament, said: "We urge both Governments to seize the moment and make votes at 16 a reality."