Thanks all.
Firstly, the lady in question's name was, according to 'legend', Elizabetta Mendosa, from what I have been told she may have looked Spanish?? Don't quote me on that though! There is/was a portrait of a lady in Spanish garb (mantilla etc) who is supposed to have been her daughter, I think...must check that!!
However, according to her marriage certificate her name was Elizabeth Mackenzie!! Her father's occupation was Stoneman, his name was James Mackenzie but the certificate doesn't state whether he was deceased or not when she married. She married in London, by the way, in Middlesex 1844. No information about siblings of hers... I only have her name and possible birthyear, although she was a few years older than her husband when they married... however, her death year and age at death (69 years in 1877) places her birthyear as being c1808. All census records have her as being from Scotland, one mentions Cromarty. Also, the census records indicate her as being born c1815. Also, these census records show her and her family (husband and child) as being in London in 1851, and Sussex in 1861 when the child was supposed to have been in a convent in Spain... long long story...
So anyway, this is my husband's family and his sisters refuse to accept the census and marriage records as being .. correct... lol so I thought I might try to see if there is any other explanation for Elizabeth to be Spanish... or having Spanish ancestry!!
I have only got as far back as her marriage in 1844. There is a possibility that I have found her in England in 1841, the name and age fits, but can't be certain of course.
Assuming that she was born in Cromarty c1808 I have found a birth record for an Elizabeth Mackenzie born in 1807 to possible parents James Mackenzie and Margaret Mackenzie nee Bain. Can't confirm this of course but it's the most likely one so far....
Cheers!!