Apologise John's death is 1850 I have the certificate I read his age on the system in error.
So this is where I got to about 6 years ago and I am now revisiting hope to find something new to clarify the link back to earlier Littlejohns but appear to be in the same mess.
I have a clear trail to William and from William to the 1841 census then it gets very unclear:
Farther is John (confirmed in William's marriage certificate) but the closest I could find was John Littlejohns born 1803 Bulkworthy
Using FindMyPast (I am an Ancestry member) I have now found a John Littlejohns born 1802 registered at Bratton Cloverlly which is more probable.
Mother is Jane (in 41 census) two apparently plausible possibilities
Jane Edd(s)(Elder) - 1805 Thoverton not good but marriage record to John Littlehons 1827 Upton Payne
unfortunately the records from this time do not contain fathers name and the witnesses are probably church officials.
Jane Davy(Davey) - 1803 Crediton perfect but unable to find any marriage record
Incomplete records for children's (in 41 census) births/baptisms with possible links to all:
Bridestowe records with mother as Jane for Mary, John & James also with MMN as Davy
Also a record for Elizabeth Littlejohns with MMN as Davy not in 41 census
Holsworthy record for William with mother as Ann
No records for Thomas or Samuel