The French decision to join EURATOM was conditioned on the regional agency not impinging on national nuclear programs. As early as 1955, French Prime Minister Guy Mollet had instructed French negotiators that “Euratom will not be an obstacle toward the possible decision of France … to build nuclear weapons.”  While EURATOM’s jurisdiction would be limited to negotiating purchases of fissile materials, promoting trade with the United States and the United Kingdom, and exchanging reactors designs and civilian technology among members of the Atlantic community, Couve de Murville credited EURATOM with a fringe benefit: monitoring West Germany. In this spring 1960 letter to Prime Minister Michel Debré about revising the treaty, he warned against the removal of EURATOM controls over raw uranium and thorium or enriched uranium. Their removal, he cautioned, would create a dilemma: “either abandon the idea that German’s renunciation of atomic armaments could be enforced or support the enforcement of equivalent controls under the West European Union, which … would interfere in the direction of our programs and the development of our nuclear weapons.”

Subsequent to De Gaulle's November 1967 veto of Wilson's EEC application, senior British ministers still saw the European question as having considerable importance. Shortly before his departure from the role of Foreign Secretary, George Brown reported to the Defence and Oversea Policy Committee that the ructions over Article 3 of the NPT would be "particularly awkward for us as potential members of EURATOM and the E.E.C." De Gaulle's second "Non!" only served to postpone Britain's membership of the EEC, as Edward Heath's Conservative government successfully campaigned for accession, which took place in 1973.

Responding to a request from Michael Palliser (Wilson's Private Secretary for foreign affairs), the Foreign Office's seasoned Europe-watcher Derek Day argued that the government needed to balance three – sometimes conflicting – UK interests. First, there was the position as a European power, particularly with regard to the ongoing EEC application. Second, there was the UK's status as a nuclear power, in which the UK shared “special responsibilities” with the US, exemplified by the UK's acquisition of Polaris submarine-launched ballistic missiles as its primary nuclear deterrent. Third, there was the desire to see a non-proliferation treaty concluded, which sometimes meant disagreement with both the United States and the Soviet Union. Day contended that the United Kingdom seemed to have been successful in positioning itself as understanding European anxieties, with Bonn having congratulated Wilson's administration on bring “good Europeans.” Day's assessment was seen and lauded by Wilson, who hoped that it was correct.

When the USSR and the USA submitted a draft non-proliferation treaty in the early autumn of 1967, British representatives were enthusiastically arguing that as a prospective member of EURATOM, any British position must axiomatically take account of European interests.  As the negotiations moved forward, though, Wilson's government found itself caught in a three-sided trap of its own devising: fearful of being labelled “bad Europeans,” anxious about being seen by Washington as “unreliable allies,” and concerned about Moscow viewing them as part of the “treacherous West.”  Balancing out these competing concerns was becoming foremost in the minds of senior ministers.

By the early summer of 1967, Foreign Secretary George Brown felt compelled to comment that "if the situation should arise in which there is a direct confrontation between the United States and Russians on one side—and the members of EURATOM on the other, on the issue of the acceptability of EURATOM safeguards we should have to consider our position very carefully: the whole success of our European policy might depend on the choice we made. For the present it should therefore be a major aim of our policy at Geneva to see that things do not reach such a state." This came only a week after Wilson formally launched the UK's bid to become a member of the EEC, and two days after De Gaulle cast doubt on Britain's fitness to join the community.

Two "Notes for the Record" from March 1, 1967, describe the vigorous discussions between senior UK government figures, including Harold Wilson, Foreign Secretary George Brown, Minister of State for Foreign and Commonwealth Affairs Lord Chalfont, and chief scientific adviser to the government Solly Zuckerman. Brown argued that "our posture on the matter should be distinctively European rather than one of supporting the United States against other European countries." Wilson was even more explicit, stating that "our approach should be that of a European power discussing the matter with European partners and not seeking to fight American battles." Wilson was keen to let Washington take the lead so that his government might avoid upsetting the French, as had happened with the debates over De Gaulle's 1966 withdrawal from the NATO command structure.

Two "Notes for the Record" from March 1, 1967, describe the vigorous discussions between senior UK government figures, including Harold Wilson, Foreign Secretary George Brown, Minister of State for Foreign and Commonwealth Affairs Lord Chalfont, and chief scientific adviser to the government Solly Zuckerman. Brown argued that "our posture on the matter should be distinctively European rather than one of supporting the United States against other European countries." Wilson was even more explicit, stating that "our approach should be that of a European power discussing the matter with European partners and not seeking to fight American battles." Wilson was keen to let Washington take the lead so that his government might avoid upsetting the French, as had happened with the debates over De Gaulle's 1966 withdrawal from the NATO command structure.

The Harold Wilson government was continually focused on the issue of demonstrating that Britain should be seen as a “European” power with interests compatible with the existing EEC membership. This high-level Foreign Office note queried what the UK could do when pulled in different directions by the need to finalize a non-proliferation treaty while avoiding unnecessary damage to its European interests. This memorandum was drafted against a background of rumblings from EEC capitals that by tacitly supporting NPT proposals put forward by U.S. officials the Wilson government was being anti-European.

Before and after de Gaulle's November 1967 veto of Britain's second EEC application, Britain's position in Europe and its relationships with existing EEC states shaped the UK's role in the NPT negotiations. Prior to 1967, London canvassed opinion in EEC capitals, particularly in Bonn. As the NPT negotiations wound their way through the Eighteen Nation Committee on Disarmament (of which the United Kingdom was a member) in 1967, British representatives reported deep-seated concerns in Bonn, Brussels, the Hague, Luxembourg City, Paris, and Rome that a non-proliferation agreement might threaten the continued functioning of EURATOM, namely that its power might be subsumed into the IAEA, opening non-nuclear-weapon states (NNWS) up to commercial espionage conducted by inspectors representing the nuclear-weapon states (NWS).

A Department of State summary of of the Arms Control and Regional Security Working Group, released during the George W. Bush administration.