ELECTORAL administrators and returning officers for the General Election have been warned to keep the postal ballot secret and told that voting tallies by political agents is illegal.

The guidance has come as a result of the experience during the Scottish Referendum when it was alleged pro-union campaigners breached electoral law by examining postal ballot papers to gauge how well the Better Together campaign was doing before the polls had closed on September 18.

The Crown Office instructed Police Scotland to launch a formal investigation into the electoral fraud allegations nearly seven months ago.

Police say they are continuing to investigate but will not comment on what progress they have made during that time.

Some complainers have raised further concern that no police action has been taken in advance of the General Election.

The Herald revealed that police twice spoke to Scottish Conservative leader Ruth Davidson as a potential witness over comments she made that postal vote "tallies" were being taken in the weeks before the referendum ballot closed at 10pm on September 18 last year.

On televised coverage of the referendum results, 45 minutes after the polls closed, Ms Davidson said that the No camp had been "incredibly encouraged" by the results of a "sample opening" of the postal ballot that she said had taken place around the country over the few weeks prior to the poll.

Complaints over her account of the postal vote "tallies" raised concerns the information may have helped inform the No campaign's decision to issue the "vow" of more powers for Scotland from the three main party leaders.

It has emerged that Mary Pitcaithly, covener of the Electoral Management Board for Scotland has recommended to returning officers in Scotland that they take particular care in making sure the law is complied with and that the secrecy requirement is explained to all those attending postal vote openings.

The moves which the EMB said "draw on lessons learned from the Scottish independence referendum" include asking that ballot papers are handled face down so that no mark on the front of the paper is able to be seen by observers.

And EMB spokeswoman said the recommendations have been "well received".

The postal vote, makes up between 20% and 50% of the counted votes. Around 800,000 people, or 19% of participants, voted by post in the referendum.

Openings to validate signatures and dates of birth are done before the official count and in Edinburgh the process was conducted at the EICC on Thursday.

Those administering the process were told that while it is open to polling observers for "monitoring" purposes it is not for sampling.

A briefing for prospective candidates and their agents in the Edinburgh constituencies says: "Must be seen to be fair, no question of interference."

It adds: "Confidence in the system depends on integrity of campaigners: Code of Conduct! Experience of 2014!"

The Electoral Commission has also advised all electoral administrators that the law prohibits tallying at postal vote opening sessions.

The advice states that under the Section 66(4)(d) of the Representation of the People Act 1983 it is "not permissible to attempt to ascertain the candidate for whom any vote is given in any particular ballot paper or communicate that information.

"This provision therefore prevents those present at the postal vote opening from attempting to ascertain the way individual ballot papers are marked," the advice says.

"Anyone attending a postal vote opening must not attempt to look at identifying marks or numbers on ballot papers, disclose how any particular ballot paper has been marked or pass on any such information gained from the session," the Electoral Commission advice says.

"Anyone found guilty of breaching these requirements can face a fine of up to £5,000, or may be imprisoned for up to six months in England and Wales, or up to a year in Scotland.

"Our guidance to both candidates and electoral administrators clearly states the law and that the tallying of postal votes is prohibited. Should anyone attempt to tally postal votes at the General Election, it would be for the relevant police force to investigate."