Seeing that the register shows that detail of the cause of death reminded me that I'd never found out where Eleanor Collister als Cannell was in 1841 or her burial register entry, only the MI:

"In memory of John Collister who departed this life Nov 20th, 1820, aged 43 years. Also two of his children, who died in their infancy. Also Eleanor, his wife, who died June 10, 1849, aged 74 years."

Checking the register for the 1849 burial turned up a surprise for me:

Burials in St Anne, Isle of Man, 1849
Eleanor Kelly als Collister, St Anne, buried June 12th, aged 75 years.

So it looks like she married again at the age of 55, ten years after the death of husband John (unless I've got it very wrong):

John Kelly, Widower and Elinor Collister Widow both of this Parish were married in presence of John Quayle and Samuel Taggart 30th January 1830 St Anne.

No mention of Cannell if it is her. But why no mention of Kelly on the headstone and why is she buried with her first husband who died 29 years before?

1841 Balladoo, Santon
John Kelly, 60, Farmer born IOM
Eleanor Kelly, 65, IOM
James Kelly, 20 Ag Labourer, IOM
Catherine Kelly, 18, IOM
Elizabeth Kelly, 15, IOM
Jane Kelly, 12, IOM

John Kelly, 80, buried Santon 2nd Sep 1862 no.184

So hopefully I haven't put pieces together from too many different jigsaws.