The Scottish National Party has demanded answers on civil service impartiality from the UK’s top mandarin, following an extraordinary admission from the most senior civil servant at the Treasury about his and his department’s stance on the Scottish independence referendum.

Speaking at the inaugural meeting of the Strand Group last night in a lecture at the Treasury entitled “The Treasury and the Union” Sir Nicholas Macpherson said that in such an “extreme” case as last year’s referendum, the normal rules of civil service impartiality “do not apply”.

The civil service Code of Conduct clearly states that a civil servant must be impartial, and not “act in a way that unjustifiably favours or discriminates against particular individuals or interests”, “act in a way that is determined by party political considerations” or allow “personal political views”.

Commenting, SNP Treasury spokesperson Stewart Hosie MP said:

“These comments are astounding.

“This is a very serious admission and it begs the question – when will this UK government next abandon impartiality? We expect the highest standards from senior civil servants. With this admission, it is clear they have fallen short.

“I have written to Sir Jeremy Heywood demanding answers on under what circumstances it is acceptable for the rules of impartiality to be suspended?

“The civil service code states that as a civil servant, you ‘are expected to carry out your role with dedication and a commitment to the Civil Service and its core values: integrity, honesty, objectivity and impartiality,’ which is ‘acting solely according to the merits of the case and serving equally well governments of different political persuasions’.

“At a time when the UK and Scottish Governments should be able to work in good faith on more powers, this raises serious questions about Scotland’s ability to have any confidence in the role of the Treasury”