I may be able to help you a bit.My grandfather (Edwin James Boyde) was from IOM,he was born about 1885, but I know he had several siblings.
I don't think any of them were born as late as 1904 but Harold could be one of his nephews,as I believe my gf was one of the younger ones.
What caught my eye was your spelling of Boyde.
How many Boydes could there be on the Isle of Man.
hopefully I can help.
Hugh Boyde
British Columbia,Canada