Hi Jean. I haven't followed all your previous posts very carefully - are you looking for the Ann Caley who married James Thomson in Liverpool? In which case she could be bapt Ann, or some-other-name - then Ann? Or are you looking specifically for the Mary Ann Caley bapt in Maughold in 1853, who might have been recorded as Margt in the 1861 census?

Everything you have suggested looks possible, but I'm afraid I don't have anything which could prove your case one way or the other. As someone wrote, you may need to look at the Presentments next time in the IoM to see whether John Caley was mentioned.

You probably saw that the name Margt was clearly written in the 1861 census entry, but Margt and Mary often look very similar in handwritten records, and perhaps the enumerator couldn't read his own abbreviations. At aged 8 she was the right age for Mary Ann Caley's Maughold baptism record. I only have Tom Corteen's transcripts of these because I haven't recorded the Caley entries from the film, but he was usually very accurate.

Father John Caley aged 67 of Port y Vullen Maughold was buried 30 June 1872 (in Maughold).

Against the theory of John Corkill giving the wrong parish (and age) for Ann Caley in the 1871 census is his giving three different birth parishes for himself, wife, and servant, so he put some thought into it. Unlike those entries which have dittos for the whole household. That entry doesn't look right to me to be Mary Ann. The main thing that bothers me is her age being 14. Someone in their 30s or 40s can lop four years off their age, but a servant aged 18 would be unlikely to say she was 14 (or to look 14), and she had older siblings who would have talked about her age while she was growing up.
Also, would she be called Ann when she was called Mary (or Margt) at aged 8?

I do think the servant in 1871 was possibly the Ann Caley who married James Thomson, because her age fits there, and the problem for you is probably caused by the Lonan parish register which has a lot of unexpected gaps – single or blocks of pages missing here and there.

I wouldn't worry about the spelling of Thomson (the usual spelling in Scotland, but usually with a "p" in England which English clerks often added).

Sue