250Kts
you are correct, there are limits to conspiracy - not trusting the count maybe going a bit far, but to answer two of your points..
1) The figures presented at the briefings and verified by independant actuaries
The figures prove the pension will need more money thrown at it to keep it viable.
No one disputes that fact. It's the ability or not (or willingness) of NATS to cover the extra cost which is the whole point of the ballot.
2) The fact that discussions have been taking place since well before the present financial downturn.
Again, correct... but it was only
after the latest valuation (bearing in mind the downturn started at the end of last summer) that the Unions got rid of the OneNATSOnePension stance (without communicating the fact to the members). Therefore the goalposts did not move until the downturn began.