William Thomas was born on 31 January 1845, the eldest son of William Henry, 3rd Baron Bolton, and his wife Letitia, youngest daughter of Colonel Crawfurd of Newfield in Ayrshire. On 13 August 1868 he married Lady Algitha Frederica Mary Lumley, eldest daughter of 9th Earl of Scarborough; they had three daughters and one son, William George Algar, who, on the death of his father on 14 August 1922 succeeded as 4th Baron. He was Honorary Colonel of the Yorkshire Hussars.

Henry Robert was born on 20 September 1846. After Trinity College, Cambridge, he was called to the Bar. On 2 August 1877 he married Henrietta Cathcart, daughter of John Randolphus de Trafford of Croston Hall, Lancashire. He died on 9 February 1915, and his wife died on 14 February 1934. They had two daughters, the eldest of whom, Kathleen Mary (1878-1948) married Sir Leslie Edmund Percy Riggs Falkiner, 7th Bt.