Officials feared Ian Paisley would attempt to take over Downtown Radio in the lead-up to the 1981 local government elections.

The bizarre prospect is outlined in classified papers detailing possible steps which the "mischief-making" DUP leader or his followers might try.

A file released today by the Public Record Office sets out 17 possible options.

It warns Dr Paisley might persist with activities including hillside demonstrations, firing flares and disrupting North-South meetings.

It also lists "probable" steps not attempted so far, including the temporary takeover of Downtown.

Other likely moves were a symbolic takeover of a Government building such as Stormont or Belfast City Hall, the establishment of a "provisional government" and "gun running - either symbolic or for real".

Another page lists the various threats and, in each case, assesses their probability. A letter of response was sent by an official in the Political Affairs Division two days later. It speculates that Dr Paisley would "continue to be a thorn in our flesh", and sets out three possible options for dealing with him.

The first, a remarkably far-sighted move, was to "try to convert him into a constructive "'Makarios' figure", adding: "We could do this by treating him as the chief representative of unionist opinion and pushing some responsibility onto his party, for example by consulting him informally on Government business. However, all we know of Paisley argues that he could not respond even if he wanted to, which is in itself unlikely."

The letter adds that "were Paisley to disappear overnight, a major obstacle to reconciliation and progress would have vanished with him".

It cautions, however, that to build up Dr Paisley would "increase his mischief-making power", with no real chance of harnessing his political weight.

The second option was to allow Dr Paisley to cause trouble until his antics were judged too destructive to continue.

It warns that if he stirred up a fresh strike or fomented paramilitary activity, it would be difficult for the Government not to be seen to take action against him.

The third, recommended, option was "try to cut the political ground from under Paisley's feet".

The letter states there is no effective unionist alternative to Dr Paisley and suggests attacking his ideas in public, and privately urging the Official Unionist Party "to get out of their rut".