Adderley, Thomas (1715–91), landowner, MP, and entrepreneur, the only son of two children of Francis Adderley, Cork landowner, and Elizabeth Adderley (née Fowkes), was educated at TCD (BA 1735, hon. LL.D. 1755). He inherited his father's estate (1719), and in 1740 married his cousin Elizabeth, daughter of Francis Bernard of Castle Mahon, Co. Cork, and widow of James Caulfeild, 3rd Viscount Charlemont – a connection that gave him entry into public life. Elizabeth died in 1743, leaving to Adderley the guardianship of her three children by her first husband. While his stepson James, 4th Viscount Charlemont (later 1st earl of Charlemont (qv)), was travelling abroad, Adderley managed his estate efficiently and regaled him with letters concerning the estate and the political scene in Ireland; his letters are preserved in the RIA, Charlemont papers, and are calendared in HMC rep. 12, app. x: Charlemont MSS, i (1891). In 1754 Adderley gave James the mansion (later known as Marino) that he had built at Clontarf, near Dublin, which remained for many years one of the seats of the Charlemonts.
Adderley was MP for Charlemont, Co. Armagh (1752–60), a pocket borough owned by his stepson, but differences between them led Adderley to seek representation for Bandon (1761–76), and Clonakilty (1776–91), both in Co. Cork, during which time he concerned himself with Dublin affairs. During the parliamentary session of 1755–6 he introduced, without success, a bill to reform the Dublin corporation. He was an original member of the wide streets commission (established 1758), presided over a committee of enquiry into the management of Dublin workhouses (1758), and introduced a bill to reform the board of paving commissioners (1773). He was treasurer (1772–83) of the barrack board (of which he had been a commissioner); but when a clerk was found guilty of embezzlement, Adderley was dismissed by the lord lieutenant, Lord Temple (qv), and was sued by the attorney general for the recovery of the money.
A progressive landlord, he established in 1748 a linen factory and a bleachyard (described as ‘one of the best improvements of the sort in the kingdom’ in a 1755 report for the linen board), with sixty-six employees, at Innishannon, Co. Cork, where he built thirty slate-roofed stone houses for the French protestant workers whom he had recruited, and a charter school for forty pupils which was opened in 1752. Mary Delany (qv) described him to her sister in 1752 as ‘one of the worthiest men in the world; he spends his life in doing good and generous actions’ (Autobiography and correspondence . . ., ed. Lady Llanover, iii (1861), 155). The linen factory flourished initially, producing high-quality material, but by 1775 it was in decline. His attempts to establish silk, carpet, and cotton factories were ultimately unsuccessful. He was admitted a burgess (1755) of Kinsale, Co. Cork, and presented with a gold medal from the Dublin Society for his plantation of mulberry trees (1766). By Elizabeth, his first wife, he had one daughter. He married secondly (1769) Margaretta Burke; they had three sons and one daughter. Adderley died 28 May 1791 at his residence in Granby Row, Dublin, and was buried in St Mary's church, Dublin.