A devolved Scotland would become a left-wing one-party state, the Scottish Office warned ministers 30 years ago.
Civil servants in Wilson's government feared devolution
Civil servants in Harold Wilson's Labour Government feared devolution would mean "considerable dangers" for the union.
Officials were also concerned it would lead to "political abrasiveness" between Westminster and Edinburgh.
The warnings were revealed in National Archives of Scotland documents which were released on Saturday.
The concerns followed the Kilbrandon Report of 1973 which recommended devolution for Scotland and Wales.
The fear of a devolved Scotland was disclosed in a report for Scottish Office ministers, marked confidential, on the "major political, constitutional and administrative implications" of devolution, dated 17 April, 1974.
The report warned: "As far as can be foreseen, Scotland and Wales would be likely either to be 'one-party states' or, at any rate, to have permanent
A hand has scribbled in the margin: "Not true."
There was also a separate report from the Kilbrandon Unit's Trade and Industry Group, dated 30 April, 1974.
It warned: "If its (the devolved assembly's) actual powers to influence and regulate trade and industry were limited there would be either political abrasiveness between Westminster on the one hand and Edinburgh or Cardiff on the other, or concessions by the United Kingdom Government.
"It seems unlikely that any concession would satisfy the discontents without
bringing problems of equal or greater magnitude.
"In these circumstances a growing cynicism about devolution and disillusion
about its supposed benefit could lead to greater pressure for separatism,
especially since oil discoveries have made separatism more attractive to many
from a material viewpoint, than devolution."
The reports were written amid concerns from pro-Union MPs over the Scottish
National Party's (SNP) gain of 11 seats in the General Election of February
But a memo in April that year from the Department of Industry's Scottish
Industrial Development Office played down nationalist successes.
A civil servant wrote: "It is of course, important to avoid over-dramatising
the growing nationalism in Scotland, and it could well be that the 22% SNP vote
at the General Election represented the crest of a wave."
The Kilbrandon Report was published in 1973 and recommended the setting-up of
elected assemblies in Cardiff and Edinburgh for a four-year fixed term.
It said Scottish and Welsh support for devolution should be tested on the
basis of referendums, which were carried out in March 1979.
Alex Salmond described the disclosures as 'fascinating'
But with the rules stipulating that 40% of those eligible must vote, the home
rule plebiscite narrowly failed in Scotland and was overwhelmingly defeated in
Scottish National Party leader Alex Salmond said the papers showed the party's gains had forced Labour to change its position and support devolution by the second General Election of October 1974.
He said: "What this fascinating document reveals is the extent to which SNP pressure transformed the government position from being anti-devolution in April
1974, when this document was written, to being pro-devolution in time for the October 1974 election.
"The lesson for today is quite clear: it's only SNP votes that concentrate the minds of Labour governments in London."