because pedigree chart is probably based on someone's guesswork ? - there are only 2 sources for baptismal records - the actual parish reg (copied in 1911 - entries derived from this are indicated as extracted records in IGI) and the Bishop's transcripts compiled each year copied from the contemporary register - these are not available on Mormon film (held at Manx Museum).

Is there an MI for Wm ? - his burial entry (assuming I have identied him correctly based on 2 children matching ages in 1841) would appear to suggest he was older.

You can borrow the film of the official copy of Arbory register and check for yourself -