Desperques, who has only missed one final in that time, booked his place first after gaining quick revenge for his Open defeat to John Skillett.
Back on his favoured Gremlin table, Desperques moved into a 2-0 lead with a pair of 70-plus point frames, and he was soon on the brink of victory with a fine 90 in the next.
Skillett, largely shut out to that point, looked to be getting on the board when leading the fourth 34-8, but Desperques stepped in with a clinical 52 clearance.
Later in the week, Glenn Le Prevost started brightly in search of a repeat final against Desperques by winning the opening two frames by 12 and two points, but Shorto slowly turned the tide in his favour – levelling the match 56-44 in the fourth.
He never looked back from that point in closing out a 4-2 win, to give himself a chance of drawing level with Desperques in their Island final head-to-heads.
In the Women’s Island Championship, Kate Le Gallez will make her fourth consecutive final appearance having beaten Danielle Leadbeater 2-0.
Following a close first frame, Le Gallez sealed her win with a 25 clearance, and now awaits the winner between Anne Le Maitre and Yvonne Bogue.
In the Norman Wale Handicap, Desperques was among the high breaks again as he fought back from a frame down to beat Dave Bullock in the quarter-final.
A 93 break levelled the match before posting a 46 to set up a semi with Antony Makepeace.
Waiting for them in the final is Ben Le Noury, who came through a tough battle to beat former finalist Pete Gallienne. Twice Le Noury led – the first time with a 26 break in the opener – but he was pulled back on each occasion.
A tense decider saw Le Noury add a crucial 22 to win 3-2.
A tough season for North Legionnaires culminated in a disappointing week as they lost in both knockout competitions. First up in their handicap quarter-final, they were well beaten by Ex-Service Recalls, with Jason Gilroy, Jim Wilson and Shaun Sylvester all winning in a 7-1 victory.
A better showing by the Legionnaires in the straight semi saw them locked at 4-4 against Imperium Strokers.
Tom Brock, who picked up the only frame in the handicap, returned to the table for the extra-frame decider, but was beaten by Kelvin Du Feu.
The Strokers face a difficult task in the final with the Sledgehammers easing through their semi 7-1.
The league champions overcame the loss of an early frame to the Hot Butts’ Jamie Le Cheminant, with Danny Marquand and Glenn Le Prevost taking all the second-half frames.
Wayne Rihoy and Chris Le Vallee have the chance of a second Pairs Handicap snooker title after winning their semi-final 3-0.
The 2013 winners were too strong for Ian Le Maitre and Mick Murphy in taking the first two frames by 40 and 50 points, but they were pushed in the last 67-53.