Hi Tim , census 1841 aged 50 , and 1851 aged 60 indicates she may have been born around 1791 , she lived at Rushen with Thomas and their children both times. Esther appears to be buried Rushen 11/1/1858 and Thomas 6/4/1859 Rushen aged 67 . Perhaps you can ask Donna Douglas to get the Memorial Inscription ( if there is one) . On the Wills site there appears to be a will for Thomas 1859 , which names all their living children. Their son Edward appears to die 1849 , first Richard 1829 . Not sure about children John and Catherine.
Thomas Q and Margaret Cross married 5/6/1791 , and appears Margaret christened 15/7/1770 in Malew , Can't seem to find a Thomas Q that suits. However you should contact Elizabeth Feisst or Malcolm Qualtrough , as they have done a hugh amount of research into the Qualtrough family on the Isle of Man . On a side issue I see that a Thomas Turnbull aged 32 died in the explosion on the Brig "Lily" on 29/12/1852 , he is not the son of Esther , but must be related.

Cheers
David Dwyer