“We are asked to permit a hundred men to go round to the house of a man who wishes to exercise the common law right in this country to sell his labour where and when he chooses, and to 'advise' him or 'peacefully persuade' him not to work. If peaceful persuasion is the real object, why are a hundred men required to do it?”

Speech in the House of Commons against the Trade Disputes Bill (30 March 1906), as published in The Speeches of Lord Birkenhead (1929), pp. 15-22.
Context: We are asked to permit a hundred men to go round to the house of a man who wishes to exercise the common law right in this country to sell his labour where and when he chooses, and to 'advise' him or 'peacefully persuade' him not to work. If peaceful persuasion is the real object, why are a hundred men required to do it? … Every honest man knows why trade unions insist on the right to a strong numerical picket. It is because they rely for their objects neither on peacefulness nor persuasion. Those whom they picket cannot be peacefully persuaded. They understand with great precision their own objects, and their own interests, and they are not in the least likely to be persuaded by the representatives of trade unions, with different objects and different interests. But, though arguments may never persuade them, numbers may easily intimidate them. And it is just because argument has failed, and intimidation has succeeded, that the Labour Party insists upon its right to picket unlimited in respect of numbers.