Final answer:
The irony in the story 'The Visitor' is not described in the provided text, nor is there explicit information on Spruce's role as a savior or the presence of feminist themes without further context.
Step-by-step explanation:
The irony in Christine Pinsent-Johnson's story "The Visitor" is not explicitly detailed in the provided text. However, situational irony generally involves an outcome that is contrary to what one would expect. If Spruce were presumed to be the savior of the town, an ironic twist could be that he contributes to its downfall or that his help comes at an unforeseen cost.
Regarding the feminist or proto-feminist themes and the preservation of the white heron by Sylvy, the texts provided do not clearly outline these aspects, hence it would be speculative to assess whether Spruce was indeed the savior or whether a feminist theme is conveyed without additional context from the story itself.