Conducted last week, the private poll drew 13 of the 25 OECD member countries to declare their preferences for first, second, third and 'acceptable' choices.
Mr Johnston, president of Canada's governing Liberal Party, won the backing of seven countries as their first choice while six more said he would be acceptable. Since the poll, two further member states have indicated informally they would back Mr Johnston.
Of the three Europeans challenging the Canadian for the job, Lord Lawson was the only one to secure support of any significance. He was first choice for two countries, second choice for five, while three others found him acceptable.
The chances of Lord Lawson, the former chancellor, of securing European backing may have been boosted by indications that the British Government has given up promoting Sir Leon Brittan's long-shot candidacy to replace Jacques Delors as President of the European Commission.
When the search for a new OECD Secretary-General began early this year, the US made it clear it wanted to end the tradition under which a European always held the position. The US is determined that the job should now be held by someone outside Europe, to better reflect the evolution of the world economy into three big trading blocs.