You can put strings on a puppet and make it dance to your tune. You can't put strings on a real boy and expect the same to happen. So says the tale of Pinocchio.
First let's clear something up. All this talk of Westminster legislating for a "binding referendum" on Scottish independence is total nonsense. There is no such thing as a binding referendum in the UK constitution. All referendums are advisory. Their force is only political and not legal. Westminster could legislate for a Referendum bill which gave specific instructions to begin a process to settle independence in the event of a "yes" vote but it could just as easily repeal that Act of Parliament and not honour the result. Their ability to lock-in a result is no greater than that of the Scottish Parliament.
The real legal issue here is whether the Scottish Parliament has the power to legislate for ANY sort of referendum pertaining to independence because of the reservation under Schedule 5 of the Scotland Act, which makes the "Union" between Scotland and England a "reserved matter" to Westminster. I have expressed my own view on the legal position, that Holyrood lacks the legal power, on numerous occasions and that has not changed.
But let's not pretend that the real legal issue is the real political one. On a political level it must be acknowledged that the SNP have a mandate to ask the Scottish people if they want to become independent from the UK on the terms specified in their manifesto. That includes when it is to be held. It is nothing short of disgraceful politicking on the part of the other parties if they try to place a sunset clause on the holding of a referendum. Westminster should amend the Scotland Act to empower the Scottish Parliament to legislate for a referendum, with access to all of the usual bodies, without ANY strings attached.
A real respect agenda towards the Scottish Parliament and those it represents requires that a basic democratic legitimacy threshold is met, and attempts to manipulate the result by forcing the SNP to hold a referendum before they said they would (in 2014 or 2015) is just crass and the Scottish people won't tolerate it. If David Cameron et al can't see that this is suicidal politicking as well as stupid then frankly they deserve to lose the referendum on that basis alone.
If those ambivalent or against independence want to remain relevant in the discussion of Scotland's constitutional future it must respect the democratic legitimacy of its institutions and let that debate take place. The Scottish people are capable of determining their own future. If independence is such a bad idea, trust them to vote accordingly as and when they asked. They aren't Pinocchio in construction. They're the real boy and strings won't hold them down.
It would, however, be inappropriate for the Scottish Government to use a separate body from the Electoral Commission to oversee the administration of the poll. Whilst I support the principle of the freedom of a separate commission (for example allowing 16 and 17-year-olds to vote) there must surely be concerns as to the independence and impartiality of a body set-up purely for the purposes of the referendum which alters basic fundamentals from the constitutional norms like suffrage. If Westminster is prepared to make the concessions they should, the SNP should be constructive on that side of the mechanics.