Here’s the link to the page in the parish register (close the gap in the ht tps):

ht tps://familysearch.org/search/record/results?count=20&query=%2Bgivenname%3Agertrude~%20%2Bsurname%3Abraucker~%20%2Bmarriage_place%3A%22isle%20of%20man%22~%20%2Bmarriage_year%3A1892-1892~

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Interesting to note that Gertrude’s signature looks like Brancker. The IGI transcription of the vicar’s spelling shows Braucker. However, if you look at all the instances of the letter n in his writing, they look more like u.

Name William Middleton Burton
Event Type Marriage
Event Date 06 Sep 1892
Event Place St Thomas, Braddan, Isle of Man
Gender Male
Marital Status Single
Father's Name James John Burton
Spouse's Name Gertrude Isabel Braucker
Spouse's Gender Female
Spouse's Marital Status Single
Spouse's Father's Name Charles Braucker

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Like you, I don’t think that the Charles Henry Brancker b 1858 is the same person as the Charles Brancker (army surgeon) who was Gertrude’s father, since CHB was a commercial clerk who became a broker.

In your tree, I think that Gertrude’s place of birth should be “Unknown, possibly Liverpool” rather than the “Severn House, Loch Promenade” which was just the address where she was living at the time of her marriage.

I’ve wondered whether she might have been born abroad----does anyone know where the British Army were likely to have been circa 1871 ?

Jean