why do all political parties refuse to allow or even discuss 'none of the above'?

Because it contradicts exactly what they want. Recognition that they are right. It also brings into question that they aren't doing what they are elected for and that is representing the people who vote for them.

You are quite right.

The government instructed my local council last year to send a consultation form to every house in the area asking them how many gypsy sites they wanted in their area. One of the squares 1, 2, 3, 4, or 5 had to be ticked. They would not allow the number zero to be shown on the form.

When the forms got back to the council, the government were then able to say that the vast majority of replies showed that local people wanted at least one gypsy site in their area. The few forms not counted in to make it up to 100% were not allowed because sensible people had handwritten none next to those 5 boxes.

Another question asked what was the public main concern in having nearby gypsy sites. The government would not allow the statement "fear of increased crime levels" to be a valid answer.

That's the way this despicable government works.

They now want the vote counting system changed, they have realised from their gerrymandering in setting up the Greater London Authority that the Conservatives need to win 13 of the 14 first past the post seats to gain overall control, an impossibility. The other 11 seats are awarded to losing candidates who invariably vote with Labour in the Authority's decision making process.

a) your question is articulate and understandable

b) none of the above

They are intellectually lazy.