THE decision by the Scottish Greens to back away from Yes Scotland is a blow to the campaign for independence, although it is by no means a fatal one.

The Greens may yet rethink their position at their conference in October – indeed, their current stance could well be a bargaining chip designed to extract maximum influence in future months.

However, it would be wrong for the SNP or Yes Scotland to dismiss the Greens' decision lightly.

For not only does it hand ammunition to the pro-union Better Together campaign ahead of its imminent launch, it also exposes a troublesome truth: it will be difficult to portray the Yes campaign as a cross-party affair if it is too heavily dominated by the SNP.

It was set up by two of Alex Salmond's former advisers on secondment from the SNP, is funded by £2 million originally given to the SNP, and is now being directed and executed by SNP strategists.

It is hard to avoid the conclusion, in its first few weeks at least, that this is an SNP campaign in all but name.

As Green Party co-convener Patrick Harvie says, it is perfectly understandable that the SNP should want some control of how its fortune is spent.

But without a formal structure such as a board or committee, the campaign will always be open to accusations that it is an SNP front.

Many within the party and the campaign itself might not be overly concerned at that - but it does fly in the face of attempts to paint a picture of a broad church.