Quote from AV leaflet
If more people vote ‘yes’ than ‘no’, when will we start using the ‘alternative vote’ system?
The ‘alternative vote’ system will be used after a review of the boundaries of the area that each MP represents (known as their constituency) is completed. This is due to happen between 2011 and 2013. The review will happen regardless of the outcome of this referendum.
At the end of the review, the UK Parliament will vote on implementing the new boundaries. If the new boundaries are implemented, the ‘alternative vote’ system will be used for all future elections to the House of Commons.
The last sentence seems to imply that the referendum can be negated by a vote on new boundaries.
What is the point then?