Hi Jean,
Thanks for that new information, it's been most helpful. Having done a bit more research I think that the second Margaret HUDSON on your 1871 census list is the person who married Thomas REID.
In the "Isle of Man Parish Registers 1598-2009" I also found the same marriage information for them as you supplied, married on the 9 July 1871 with Margaret's last name as HUDSON aged 23 which would mean she was born in 1848.

I have also found an "Isle of Man Marriages 1606-1911" for Thomas REID to Margaret HUDSON for the same date as above and the same father.
There were no marriage records for her with the surname of Hudgeon.

I looked up the census for 1871 and found the one for Lime Street and the head of the house (John HUDSON) & her age & birth date seem to match. Another interesting point is that her father was a mariner - so too was Thomas REID and as the census showed they had boarders - this may be how they meet?

I have also found records of her children to Thomas REID with Margaret's surname as HUDSON so get a stronger feeling that this is her (Children Anne or Annie b1872 & Elizabeth Margaret b1874).
Another factor that gives me the feeling that I'm now on the right track is that when Thomas REID re-married in 1876 to Catherine KERRUISH, they had four children. Their third child (b1882) was a son named Thomas Henry Hudson REID. We always wondered where the Hudson came from. So there is now evidence of it as a family name (Thomas Henry Hudson REID was my great-great grandfather).

I'm still sure Margaret died between 1874 and 1876 but have not found any information about that so far.

Thanks so much for your help Jean and if anyone else has any information to share it would be most appreciated.
Kind regards Sharon Reid.