Officials locked antlers after proposals to put an Irish elk on a new pound coin in Northern Ireland prompted a royal row in 1986.
The extinct deer, which is commonly associated with power or strength and had been used by the former government of Northern Ireland, was seen as "broadly acceptable" to nationalists and unionists, a memo in the official files disclosed.
But it stumbled into rougher ground after someone pointed out using the symbol on a shield did not have the status of a royal badge and there was no time to apply for a special warrant.
The prehistoric animal was famed for the size of its antlers, which spanned up to 4.3 metres and weighed 45 kilogrammes.
Fossils have been found in large numbers preserved in Ireland's peat bogs.
Whether to emboss the relief of the noble-looking animal on the new coin had been deferred in 1986 after the Royal College of Arms said a new badge for Northern Ireland would have to be granted by the Queen, according to documents disclosed by the Public Record Office of Northern Ireland (PRONI).
The College said the elk would have to be shown on a heraldic shield and this in turn would require a badge.
The note said: "Advice at that time was that a new royal badge for Northern Ireland could be politically contentious and therefore we opted not to pursue the elk on a shield device proposed at that time."
The matter resurfaced in 1991 following a decision by Treasury ministers that a series of new designs for the coin be introduced representing the constituent parts of the UK. Northern Ireland's old depiction of a flax plant was to be replaced.
To create a royal badge expressing sovereignty over Northern Ireland alone would reflect on the status of the existing badge, the crowned harp which was used by the RUC, and would require amendment of the Royal Arms to show loss of sovereignty over the Republic, an official wrote.
One civil servant noted this would be a political hornets' nest.
Finally, after much consideration, the NIO confirmed that the Northern Ireland Secretary had agreed to an image of an elk without the problem-causing shield.
Fairly well known symbols like the Red Hand and Crown, the six pointed star, harps, shamrocks and the Cross of St Patrick had been avoided in the past, the record said.