On the other hand, there is a line in the second half of the song that seems possibly to be an allegorical allusion to London changing hands in the Wars of the Roses(which would put it firmly in the Edward IV era.

My colour is changed since thou seest me last

My favour is vanish't my beauty is past,

The rosie red blushes that sat in my cheecks,

To paleness is turned, which all men dislikes.

All very intriguing eh? I think we all need some expert 14th/15th century historians here.