Jones was a figure of the court, and most commissions for large houses during the reign were built in a style for which Summerson's name "Artisan Mannerism" has been widely accepted. This was a development of Jacobean architecture led by a group of mostly London-based craftsmen still active in their guilds (called livery companies in London). Often the names of the architects or designers are uncertain, and often the main building contractor played a large part in the design. The most prominent of these, and also the leading native sculptor of the period, was the stonemason Nicholas Stone, who also worked with Inigo Jones. John Jackson (d. 1663) was based in Oxford, and made additions to various colleges there.