by 'broke forth' the politician is talking about Winston or his party having at some stage taken government seats in the South, and that the writer having lost out down South, was hoping to take Dundee in the North with their assistance! I interpret it as 'their loss would be Dundee's gain'. I don't know much about politics in the 1900's, so don't know the background.   However, the writer was using a 'locally' focused song. He then turned it to a new political use, in a witty way by appealing directly to the natives (yet only gives initials at the bottom, very odd).

There are several other verses, but I thought it was a good example of parody for propaganda. I just came across it looking through old newspapers.