see some of my comments at www.manxnotebook.com/famhist/genealgy/church.htm

there can sometimes be a very long gap between a private baptism and reception (in German c 1800 there were a very few with several years gap - possibly the family had moved away or they wern't too concerned with the reception (their child had already been 'done') - possibly a lax vicar/clerk who didn't chase the family.