The Scottish Government was quick to respond to today's report by the Commons Public Administration Select Committee on civil service impartiality during the referendum campaign, claiming that the report vindicated its objections to the UK Government's publication of a senior civil servant's warning against currency union.

However, neither side in the referendum should take any kind of comfort from the report, as it is equally damning of both of them. Instead, all the parties should now seek to learn lessons for future political campaigns to ensure the important principle of civil service neutrality is not broken again.

The committee's report, which gathered evidence from ministers and officials working for the Scottish and UK Governments, focuses on what it sees as two fundamental breaches of the Civil Service Code - the document which sets out the standards of behaviour expected of all civil servants to uphold the service's core values, including objectivity and impartiality.

The first breach concerns the Permanent Secretary to the Treasury Sir Nicholas Macpherson's warning against sharing the pound with an independent Scotland, which was made public by the UK Government ahead of it ruling out a currency union. The Treasury and Sir Nicholas have consistently defended the decision to publish the advice on the grounds that the referendum was an exceptional case, but the select committee is having none of it. The decision to publish, it says, compromised the perceived impartiality of one of the UK's most senior civil servants.

The committee's second major criticism is just as clear-cut and damning, although this time it is the Scottish Government that is the target. The White Paper on independence, says the report, included promises the SNP could implement only if the party won the 2016 Holyrood election, and to that extent it did not uphold the factual standards expected of a UK Government White Paper. The report says the White Paper raised questions about the use of public money for partisan purposes.

Both criticisms are entirely fair and could not have come at a more relevant time - just days before the end of the current session at Westminster and the beginning of the traditional purdah, which restricts the activities of civil servants ahead of a general election. Rules such as the period of purdah are there for good reason: civil servants are paid from the public purse and during elections must act, and be seen to act, in an objective and neutral way.

What the select committee's report has highlighted is a lack of clarity on how such rules apply to referendums. Both the UK and Scottish Governments broke the rules at the height of the campaign last year, and yet neither side has accepted that yet. In some ways, that is typical of the fractious to-and-fro between Westminister and Holyrood we have all grown used to, but the lack of clarity on referendums cannot be allowed to continue, not least because we could be voting in another one on Europe, should the Tories win a majority in May. The prospect of another referendum on Scottish independence is also real.

As the select committee recommends its report, the Code of Conduct should now be amended to include specific advice on referendums so that any future ambiguity can be avoided; the change to the code should also be made in good time for any possible referendum on Europe in two years' time. We may all become more used to voting in referendums in the years to come, but the civil servants and ministers who are paid from our taxes should be in no doubt about how they should, and should not, behave during them.