Geoffrey Van Orden CBE, former leader of the Conservatives in the European parliament, writes: Over dinner in Brussels in January 2002, I put it to David Trimble (obituary, July 25) that one of the greatest strategic errors of the Northern Ireland Unionists and British government was to make little effort to rally those of Scots-Irish background in America to speak out against the Irish Republican caucus (those who support the Irish Republican cause - Sinn Fein/IRA for short) in Congress.

This left the field open to the IRA activists and their sentimental apologists and ignored the large number of Scots-Irish migrants to America — the largely Ulster-origin families, many of which had risen to leading positions in American political and industrial life — indeed, 17 Ulster Scots had become president. David agreed the point while observing that, generally speaking, the Protestant Irish migrants had assimilated more rapidly into the wider population and were more dispersed than their Irish Catholic counterparts and so were less easy to mobilise.