Some further information on the song which might explain the transference of "weaver ?" to "Ferranti lad".
As I remember, the Ferranti factory near Oldham made power generation equipment of the sort that goes into power stations. It was part of the heavy industry of the north-west.
[The Ferranti Electronics factory (computers & radar etc) was in south Manchester.]
Ferranti workers in the song would be manual/semi-skilled labour, which fits the context better I think.