Geoff - there were other Mary Sharps of a similar age living in Boston in 1841, so it could be that the death you found is one of them.There other deaths of Mary Sharps in Boston:Oct-Dec 1846 aged 1 at ButterwickApr-June 1852 aged 17 at FreistonOct-Dec 1854 not sureOct-Dec 1856 aged 81 at SwinesheadOct-Dec 1857 perhaps aged 46 at Fishtoftplus the 1860 one you found (at Boston) and other later ones.I suppose the only sure way of finding out which Mary is the correct one is to get a death certificate and hope that the informant is one of her children, It would be a good idea to search Lincstothepast to find burials relating to the above deaths to rule out any which are totally the wrong age.