I looked at the death of Ann McGill or Henderson. She is described as the widow of William Henderson, miner, and daughter of Morton McGill and Ann, maiden surname not listed, or it might be McGill again.
So William was alive in 1861, but dead by 1872. Sure enough, he died in Whitburn in 1867, parents Peter Henderson and Agnes Thomson.
From the 1851, 1861 and 1871 censuses noted upthread William and Ann/Agnes McGill had
William, born 1846/7
James, born 1848/9
Agnes, born 1851/2
John, born 1852/3
Isabella, born 1862/3
From the IGI, they had
Marion, born 4 December 1857
Marion, born 8 December 1859
Isabella, born 23 May 1862
Margaret, born 10 May 1865
Of those, only Isabella was with her parents in 1871.
Marion Henderson, aged 0, died in Whitburn in 1858
Marion Henderson, age not listed, died in Whitburn in 1860
Margaret Henderson, aged 2, died in Whitburn in 1866