Sentence:  In the autumn there was a row at some cement works about the unskilled labour men. A union had just been started for them and all but a few joined. One of these blacklegs was laid for by a <WSD>picket</WSD> and knocked out of time. 
Meaning of the word marked with <WSD> tags:  A protester positioned outside an office, workplace etc. during a strike (usually in plural); also the protest itself.