EU prime ministers were warned by their Irish counterpart never to hold a referendum because “all governments are unpopular”, according to formerly top-secret Downing Street files.

The high-level advice is among political revelations contained in the latest files released to the National Archives in Kew. The papers also include John Bercow’s left-baiting curriculum vitae and John Major not going to the Olympics because he might miss a Lords Test match.

Ireland’s prime minister, John Bruton, was among those attending a European Union heads of government summit in Mallorca in September 1995, at which Jean-Claude Juncker, then Luxembourg’s leader, described pessimism about the EU as “a storm in a teacup”.

The file, classed as “Top Secret: not to be taken out of Number 10 Downing Street”, records that the taoiseach gave “the day’s most amusing and original intervention, punctuated by laughter”.

In his talk, Bruton observed: “All governments are unpopular. Given the chance, people would vote against them in a referendum. Therefore avoid referendums. Therefore don’t raise questions which require them, such as the big versus the little states.”

The documents contain a dismissive description by Roderic Lyne, John Major’s principal private secretary, of Juncker as “lightweight and faintly ludicrous”.

John Bercow, recently retired as Commons speaker, appears in a file on political advisers in Whitehall. His CV, reflecting his early political enthusiasms, shows him determined to impress Conservative ministers.

Between 1986 and 1990, when he was deputy Tory leader in the London borough of Lambeth, Bercow wrote: “Exposed waste and corruption by the extreme left in control of the council. Fought against leftwing policies, double standards and dirty tricks campaigns by Liberal Democrat councillors.”

His devotion to the cause worked, securing him a place as special adviser to the chief secretary to the Treasury in February 1995. Bercow has said that his political sympathies, which started out on the hard right, have since tacked back towards the centre.

Major’s devotion to cricket is well known. A file on a possible overseas trip for him to the 1996 Atlanta Olympics shows, however, that it may have been a pivotal factor in preventing him visiting the Games.

A memo from Rachael Reynolds in his office in June that year noted that: “I understand you are thinking of staying here for the Lords Test in preference to going to the Olympics ... Turning to the disadvantages of you going: First and probably most relevant is that you will be very tired at the end of July. The programme is not likely to make that worse but it is a long flight and the weather will be hot in Atlanta at that time.

“Second, you will miss the Lord’s Test and we are unlikely to be able to pick up a satellite channel in America which carries cricket (do they do ball by ball commentary on the World Service?).”

Reynolds failed to persuade him to attend the Olympics, despite listing “more pros than cons” and telling him: “You have established your street cred in this area so well, it would be a pity to miss an opportunity which only comes up every four years.”

In the end she had to inform the British Olympic Association: “The prime minister has decided that his programme as the end of July is too heavily committed for him to be able to travel to Atlanta.”