Gaffy,
I thought I had seen a return which said Ganley, Ireland, rather than what you correctly say is the 1861 return, which says Irland (sic), Ganley but I'm not finding it at the moment. I think I have her unmarried, as Mary Hughes on the 1851 census but that only gives her birthplace as Ireland. The address is Court 10, 4 House, Slaney Street, where the Hughes family is lodging with the Feeney family. Ref HO 107 2057
Since John Booth was living with Eliza Orme, formerly Lovett, by 1863 and the christening of his youngest child with Mary Hughes was in 1860 there is a distinct possibilty that Mary had died between these dates, though I can't find a death registration.
Keith