Do you have your original Birth Certificate? He may be mentioned on there.
The alternative would be Parish Records, but you would need to know in which parish?
Also Parish Records this late are likely to be still at the relevant church.
Or available art the Manx Museum Library, but they would have to retrieve from the archives.
But I have to say that, in researching a Manx friend's Family History, where all of his father and siblings were illegitimate, I can find no mention of a father's name on either certificates or PR entries.
