Their hosts are the cross-legged knights. That is, the stone effigies of the Round Church. In this church at one time lawyers met their clients, and here a host of vagabonds used to loiter about all day, under the hope of being hired as witnesses. Dining with the cross-legged knights meant much the same thing as dining with duke Humphrey (q.v.).
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894