I was given a pencil to mark my ballot paper this evening is his right, surely a pen would have been better ?

really? I was given a pen. Strange. Which polling station did you go to?

Interesting question! Although the mark of a pen is more difficult to erase, it is still very easy to spoil a ballot marked with a pen, for example by adding another mark and thereby making the ballot invalid. Also, pens tend to be more expensive than pencils. No matter what type of marker that is used, the consistency is important - the use of both pens and pencils can create confusion.

This topic is covered by the ACE Encyclopaedia section on Voter Service/Issue and Casting of ballots:

"In systems where preferences have to be marked on ballots, the method used to mark a paper ballot has cost implications. Pens are more expensive than pencils, and more likely to be taken as a souvenir by voters.

Pens offer no greater integrity; a voter's mark with a pen can be as easily overwritten as a pencil mark can be erased. However, where there is wide public concern about election integrity, use of pens may enhance the image, if not the reality."

Read more at http://aceproject.org/[…]/vog02b03

I find this hard to believe! Pencil can be easily earased by anyone who may tamper with a voting machine. PEN should be used.

In my country, Italy, the electoral officials will provide the voter a "special" pencil (called "copying pencil" or "matita copiativa") which cannot be deleted, and he/she must return it immediately to the officials (or face a costly fine!). The mark on the ballot paper can be removed only if scratched away.

This pencil has been used in Italian elections for the past 60 years and I think that it represents a good alternative to the more "expensive" pens.

I was given a ballot and told to put it directly in the ballot collection box.I didn't mark the ballot. My vote was not recorded. I QUESTIONED what I had done, and quickly asked for another ballot. I did vote for my candidates,but some people wouldn't have realized what happened.