The best I could find for a John Mylchreest born 1864 in a quick look at the 1871 census is:

John S. aged 9 (1862/61) son of John in Castletown, Malew. It says born Patrick, which could mean Foxdale connections i suppose. If he grew up in Castletown he might say he came from Malew, perhaps. Only thing is it gives father's occupation as Landowner - bit of a comedown to be a labourer in 1888.

RG10/5771 f.217 p.23
Douglas Rd, Castletown, Malew
John Mylchreest, h, m, 53, landowner, b. Patrick
Alice, w, 42, b. Lancs
Thomas, s, 12, scholar, Patrick
John S., s, 9, scholar, Patrick
Alice B., d, 6, Patrick
Jane Christian, servant

There was also a John Mylechreest aged 6 in Court 5, Michael Rd, Peel, but although his father was a mariner his name was Paul (wife Ann).

Not sure if any of this helps.