Lord Williamson of Horton: Senior civil servant whose skills allowed him to steer a course acceptable to both London and Brussels

At the top of the many letters Margaret Thatcher wrote about shaking up Europe, there would be the note: “cc Williamson”. All through the Prime Minister’s tempestuous relationship with her continental counterparts until her fall in 1990, the calm wisdom of a diminutive, rubicund former classics scholar called David Williamson smoothed the waves and steered a course acceptable to both the British and the Brussels projects.

As head of the Cabinet Office’s European Secretariat between 1983 and 1987, he is considered, with contemporaries such as Sir Michael Butler (obituary, Independent, 9 January 2014), Britain’s permanent representative in Brussels, to have charted the course for Britain’s 66 per cent “rebate” agreed at the Fontainebleau summit of 1984. Thereafter, as Secretary General of the European Commission in Brussels from 1987-97, Williamson piloted the Single European Act, which was signed in 1986, providing for unimpeded internal trade and greater political co-operation. Williamson is also credited with much of the preparation of the Maastricht Treaty, which established the European Union with a view towards monetary and political union in 1992.

For his prowess the former civil servant at the Ministry of Agriculture, Fisheries and Food, later Sir David, was to be ennobled as Lord Williamson of Horton, eventually becoming convenor of the crossbench peers in the House of Lords.

Williamson’s talent and felicity was that he got on well both with Thatcher and her European bogeyman, the former French finance minister – and from 1986 President of the European Commission – Jacques Delors, whose vision of a future united states of Europe would prompt her in 1990 to exclaim: “No, no, no!”

Having already acquired a quiet authority at home as Cabinet Office European secretariat chief, in which all of Whitehall paid him attention as Thatcher’s principal adviser on Europe, in 1986 Williamson delighted Butler’s successor as Brussels permanent representative, David Hannay (now Lord Hannay), by resolving with his own understated charm a tense stand-off about the Commission’s staffing.

This happened after the Commission’s first, and until then only, secretary general, the Frenchman Emile Noël, had announced his retirement at the end of 30 years’ service. London had put Williamson’s name forward as his successor, and had been surprised when nothing happened for some months, with Delors showing no sign of making up his mind.

“Finally,” Hannay recalled, “I suggested a high-risk gamble. I would simply suggest to Delors that he take advantage of one of Williamson’s frequent visits to Brussels to have an informal meal with him and clear his mind on the succession to Noël. London agreed and Delors agreed, and at the end of a dinner à deux, Delors offered Williamson the job. I never met anyone who regretted that decision.”

Williamson agreed with Delors to speak French when chairing meetings, and transformed the very personal style of Noël – deemed “not a methodical manager” and even “like a monk from the Middle Ages” – into an approach more suited to the large and complex body the Commission had become.

Williamson, it appears, enjoyed a better relationship with Delors than had Noël, to the extent that some European Commissioners, notably Britain’s Leon Brittan, felt, it has been suggested, that that very loyalty to Delors left them marginalised. Neither did Williamson’s presence at the heart of European affairs deter Thatcher from criticising the Commission for its centralising influence in her “Bruges speech” of 20 September 1988, when she lashed out at Delors, declaring, “We have not successfully rolled back the frontiers of the state in Britain, only to see them re-imposed at a European level with a European super-state exercising a new dominance from Brussels.”

Nevertheless Williamson treasured, he later recalled, “a piece of torn green blotting paper, on which, after a discussion between Margaret Thatcher and me, in the margins of a European Council note, she wrote: ‘I agree. Margaret Thatcher’, and then again ‘I agree. Margaret Thatcher’. In the field of European affairs that may not be unique, but it is certainly rare.”

His own academic rigour, learned at Tonbridge School and at Exeter College Oxford, where he read Literae Humaniores (classics), was satisfied by hers: “she always listened carefully to briefings and did not make up her mind until she had heard the facts and arguments.” Once, he recalled, “I was present in No 10 on one occasion when Mrs Thatcher came down the stairs and said to me, ‘I have read every word of the Single European Act.’”

Meanwhile the achievement that is largely attributed to the behind-the-scenes work of Butler and Williamson – the budget rebate – had by time of her death in April 2013 brought home about £70 billion to the UK taxpayer, as Williamson noted in his tribute to her delivered that month in the House of Lords.

Williamson learned the art of complex negotiation in the 1960s when as a First Secretary (Agriculture and Food) in the Diplomatic Service he was sent to Geneva for the “Kennedy Round”, the sixth session of the talks for the General Agreement on Tariffs and Trade, which took place between 1964 and the signing of the international agreement in 1967.

Soon after his joining the Ministry of Agriculture, Fisheries and Food in 1958 he had already been picked out as a suitable private secretary to the Permanent Secretary, and also to successive Parliamentary Secretaries. A 2nd Lieutenant with the Royal Signals during his National Service, he rose to become Principal Private Secretary to a number of Ministers of Agriculture, and was promoted to Under-secretary in 1974. Already he was dealing with European affairs because of Europe’s Common Agricultural Policy.

In later life he and Lady Williamson lived in Taunton, Somerset, where his long-practised precision of observation continued, with a note, made in the same neat hand so often read by the leaders of Europe, listing eight different types of garden birds, including chaffinches, goldfinches, robins and dunnocks.

ANNE KELENY

David Francis Williamson, public servant: born Whitstable, Kent 8 May 1934; CB 1984; GCMG 1998; cr 1999 life peer; married 1961 Patricia Margaret Smith (two sons); died Taunton, Somerset 30 August 2015.