(bc. 1686; d London, June 8, 1746).
English architect of Italian origin. Apparently a Venetian, he was at the court of Elector Johann Wilhelm of the Palatinate at Düsseldorf from 1708. There he was influenced by the architect Count Matteo Alberti (?1660–1716), with whom he probably worked on the Elector’s hunting-lodge, Schloss Bensburg, near Cologne. Alberti was an admirer of Inigo Jones, and it was Jones who also became Leoni’s model; this is particularly evident in the earliest known designs made after his move to England c. 1714. These were proposals for rebuilding Wrest Park, Beds (prepared by July 1715), for Henry Grey, 1st Duke of Kent. The surviving proposal (Bedford, Rec. Office, Lucas and Dingwall MSS) shows a house with two internal courtyards divided by an axially placed hall, leading to a saloon at right angles to it on the garden front. The source appears to be John Webb’s unexecuted project (1649...