The absence of detail - from either the Tories or the SNP - makes it hard to judge the effect of the policy, but the claim by George Osbourne, Shadow Chancellor
If the system had been introduced in the 2008 Budget, fuel would currently be 5p cheaper.Gives you some idea of the utter modesty of the proposal.
Perhaps Mr Allan or Mr MacNeil would let us know how much their proposals would save? Although I suspect they are mouthing a policy they do not understand and which is desperately in search of an intellectual and economic foundation. Otherwise Alex Salmond (former economist) would surely be explaining exactly how it would work.
As previosuly mentioned, the impact on duty claims by fishermen and bus operators would be horrendous. But leave that aside for the moment.
But there is another side to this policy.
If fuel duty falls when the oil price is above a certain point (so as to give the same yield to the Treasury), then perhaps Mr Allan or Mr MacNeil - or even Mr Osbourne - could enlighten us as to what that base yield is to be. Just what is the starting point?
Let us just say it is £1 per litre and whatever yield that gives.
So what happens if petrol prices fall below that point?
Why pump prices don't go down very quickly, as the deadening effect of the regulator preserves the yield to the Treasury by keeping prices artificially higher. Ooops. This might explain why the specifics are slow in being forthcoming.
The real issue is - of course- dependency on oil. As in the 1970's a price shock should be causing us to fundamentally review how and why we are dependent on fossil fuels which have a limited lifespan.
Pandering to the every whim of the electorate in the short-term leads to long-term problems. Whether that is in dealing with education in the Western Isles or ignoring energy issues, the blame lies fully with the politicians who are more interested in protecting their job and benefits than in doing what is best for the communities they represent.