 For almost 20 years he was a crucial figure in the Irish Government, which relied on him on to manage the Irish House of Commons, a task which he performed with great skill and tact.Tisdall was almost all-powerful until 1767, when George Townshend, 1st Marquess Townshend arrived as Lord Lieutenant of Ireland.Townshend had a mandate to restore the direct power of the Crown over Irish affairs and to bypass the Irish political managers like Tisdall.