Sell. After the radio series came to an end, Patterson and Leveson began discussions with the BBC on creating a televised adaption of their concept. However, the broadcaster was hesitant on making the move, leading to the pair being approached by Channel 4, who eagerly liked the idea, and securing a deal from the producers to bring the programme to their channel. The move to television was initially hit with a problem, as while it was desired for the regular cast to appear on the first televised series, Fry had begun to dislike conducting improvisational comedy. The matter was resolved by allowing him to pull out, with Sessions convinced by Fry to remain as a regular performer for the first series. In addition, Sell was unable to perform on the programme, resulting in Richard Vranch - a member of improvisational group, The Comedy Store Players, based at London's Comedy Store - becoming the resident musician for much of the programme's broadcast. Whose Line proved a success when aired on Channel 4, effectively helping to boost the careers of some of its regular performers that appeared during early episodes, including several members from The Comedy Store Players - these included Paul Merton, Josie Lawrence and Sandi Toksvig. At times, the programme also featured a number of celebrities who made occasional appearances during the earlier series, such as Peter Cook, George Wendt, and Jonathan Pryce. While the programme drew from the talent of British comedians, it also expanded to recruiting those from the United States; comedians such as Greg Proops and Mike McShane added considerably to performances, with some episodes in the third and fourth series filmed entirely within New York and thus drawing talent purely from American performers. By the fifth series, several regular performers discontinued their involvement, yet the show was greatly enhanced by the involvement of fresh talent by this time - British comedian Tony Slattery, American comedian Ryan Stiles, and Canadian comedian Colin Mochrie, improved the reputation of the programme and provided more diverse comedy and favorable viewing figures, effectively becoming prominent regulars in episodes. As series progressed, the viewing figures of Whose Line began to drop after reaching the peak of its popularity following the sixth series. Part of the problem was due to the constant use of regular performers, including Stiles and Mochrie, leaving little room for new talent to be showcased on the programme, with