That's alright, Fred, it happens to us all!
Yes, I noticed that John baptised in 1770 with a brother Richard (1772) both s/o John. He certainly couldn't have married at age 12, so it's either a late baptism or the wrong John!
I'm not sure if a fiche of the Holme on Spalding Moor parish records is available at the East Riding Records Office - some of the parishes nearer York are actually held by the Borthwick Institute in York - but, if they are at ERY, I'll check for you next time I go. I'm afraid it won't be this week though - probably next.
If it was a late baptism, it might just say how old John was in the records.
Jill