SEASON 1 - SEASON 6 Len Goodman, Arlene Phillips, Bruno Tonioli & Craig Revel Horwood The Originals: Craig, Arlene, Len and Bruno kicked things off in 2004 Strictly Come Dancing burst onto screens 16 seasons ago, in 2004. The original line-up featured Bruno Tonioli and Craig Revel Horwood, both of whom are still on the panel in its current form. The two long-standing stars were joined by original head judge Len Goodman. The trio of dance pros were joined by Arlene Phillips, through to 2008, which marked Arlene's final season. SEASON 7 - SEASON 9 Len Goodman, Alesha Dixon, Bruno Tonioli & Craig Revel Horwood Controversy: Arlene was out and Alesha was in for Strictly 2009 - 2011 Having taken part on the series as a celebrity contestant, Alesha Dixon joined the panel in the first Strictly shake-up. Arlene was given the boot, after six seasons, with the BBC stating that the show needed a refresh. This decision courted controversy at the time, with fans accusing the BBC of discrimination against older women on television; the BBC, however, strongly denied this. Alesha had appeared on season 5 of Strictly and had won it, with dance partner Matthew Cutler. SEASON 9 Guest Judge: Jennifer Grey Stand in: Dirty Dancing's Jennifer Grey filled in for one week in 2011 Head judge Len had to sit a week out and was replaced with Jennifer Grey - star of Dirty Dancing. Jennifer was the winner of the 11th season of Strictly's US counterpart Dancing With The Stars. In Len's absence, Craig was head judge. SEASON 10 - SEASON 14 Len Goodman, Bruno Tonioli, Craig Revel Horwood & Dame Darcey Bussell Darcey dances in: Dame Darcey Bussell was drafted in alongside remaining stars Len, Bruno and Craig after Alesha jumped ship for BGT Alesha swapped Strictly for the Britain's Got Talent judging desk, leaving a spot to fill for the dance series' 10th season. This was when renowned ballerina, Dame Darcey Bussell was drafted in alongside remaining stars Len, Bruno and Craig. This wasn't Darcey's first time behind the desk; she was a guest judge from the quarter final onwards on season 7 of the show. SEASON 12 Guest Judge: Donny Osmond Special guest: Donny Osmond was a fifth judge during the third week of Strictly 12 In the third week of Strictly season 12, American enterainer Donny Osmond joined the four regular judges behind the desk. This meant that the maximum score that week was 50 points. He was also that week's musical guest, performing Moon River live on the show. SEASON 15 - SEASON 16 Shirley Ballas, Dame Darcey Bussell, Bruno Tonioli & Craig Revel Horwood New head judge: The most recent incarnation of the panel has featured Shirley Ballas in place of Len Goodman The most recent incarnation of the panel has featured Shirley Ballas as head judge, after Len stepped down from the role after 14 seasons. Len announced his retirement from the show, which left speculation rife as to who would be the next head judge. While many thought Craig would be given the role, Shirley was appointed the job. Flitting between LA and London, Shirley announced she was relocating permanently to the UK in 2019, suggesting she won't be going anywhere any time soon. SEASON 16 Guest Judge: Alfonso Ribeiro Carlton steps in: Alfonso Ribeiro stepped in one week in October when Bruno could not appear in 2018 Fresh Prince Of Bel Air actor Alfonso Ribeiro stepped in one week in October when Bruno could not appear in 2018 The actor was well-known for playing Carlton in the American sitcom - famed for his own dance moves. All rights reserved for this news site dailymail and under his responsibility