La Touche, John David (1732–1810), banker and landowner, was born on 21 August 1732, a surviving son of David La Touche II (qv), banker, and Mary Anne La Touche (née Canaseele), of Dublin. John La Touche inherited £7,000 a year and the estate at Harristown, Co. Kildare. He, his elder surviving brother David La Touche III (qv), and his younger surviving brother Peter La Touche (qv) each had a one-third share of the bank. John and Peter La Touche left the general running of the bank to their elder brother and devoted more of their energies to expanding and improving their estates.
John La Touche set about improving Harristown from c.1785; he walled his demesne, built a new bridge, and secured an act of parliament to change the route of the Naas to Dunlavin road. He also resided at town houses on Merrion Square and Ely Place, Dublin. In 1783 he was one of the original members of the board at the Bank of Ireland (though he resigned after one year). Like other members of his family he was involved with charities and was treasurer of the House of Industry in Dublin c.1800. He stood unsuccessfully against the son of the duke of Leinster (qv) for a Dublin city seat in 1767, and eventually sat for the boroughs of Newcastle (1783–90) and Newtown (1790–96). John La Touche was returned to serve Harristown in 1797 but sat for Co. Kildare instead in the Irish parliament (1797–1800) and in the UK parliament (1801–2). He died 3 February 1810 and was buried at the mausoleum near Carnalway church, Co. Kildare.
He married (9 December 1763) Gertrude, daughter of Robert Uniacke Fitzgerald of Corkbeg, Co. Cork. Their eldest surviving son, Robert (1773–1844) served as MP for Harristown (1794–1800), and for Co. Kildare in the UK parliament (1802–30). Their other son, John (c.1775–1820), was MP for Newtown (1796–7) and Harristown (1797–1800) in the Irish parliament, and for Dublin borough (1802–6) and Co. Leitrim (1807–20) in the UK parliament.