The win slightly flattered Cashmere, since Caversham had a couple of early chances to score, and at top level those chances have to be put away, or else.
There was half an hour of tough tackling play, with sheets of rain driving the length of the pitch. Initially, the wind favoured Cashmere, which launched several strong shots that goalkeeper Callum Flaws handled capably.
Then the visitors hit a purple patch that started with a 31st minute goal by Shawn O'Brien, who celebrated his 100th game for the Christchurch side, by going on to hit a hat trick.
O'Brien was partnered in attack by big Liam Oxley, a builder from London who initially became coach of the Cashmere women's side, but soon earned a regular place in coach John Brown's senior side.
It was a classic smash and grab pairing. Oxley used his body mass well to hold the ball up, showing surprisingly good skills for a big man, and he made some deft passes.
Caversham missed defender Jude Fitzpatrick, and the scoring threat of Otago Golden Boot winner Tom Jackson, but Cashmere was also below strength without former captain Dan Terris and Danny Boys.
In attack, young Lewis Jackson was too often isolated, and Cashmere captain Tom Schwarz marked him tightly. Caversham's German, Tore Waechter, and Seamus Ryder also pushed forward, and it was Waechter who missed the best scoring chance of the first half in the 18th minute.
But the match was won in midfield, where All White Aaron Clapham combined well with former Scots professional Stu Kelly and Andy Barton, who won the majority of ball possession for Cashmere.
Andrew Ridden accepted the challenge in midfield, and made some dangerous runs for Caversham, but it was Cashmere who created more effective attacks.
After 36 minutes, a defensive muddle had Caversham concede an own goal, then a minute later in acres of space, striker O'Brien redirected a right wing cross with a looping header that made the score 3-0 at half time.
Coach Tim Horner probably generated some heat in the freezing Tahuna dressing rooms with his halftime team talk, and Caversham played its best football at the start of the second spell.
Slick passing and good running off the ball had Cashmere under sustained pressure, and a string of throw ins, free kicks and corners produced goal scoring chances in the crowded goal mouth.
Yet when Caversham's goal did arrive, it was from a typically deceptive run by Jackson that found space and he calmly struck an accurate shot past keeper Danny Knight to narrow the score to 3-1.
Spring like sunshine added contrast as Caversham poured forward seeking to gain more advantage.
But in Cashmere's backline, the Schwarz brothers Tom and Dan did not panic, and joined by substitute Jordan Halligan, son of former All White Danny, the Christchurch side closed defensive ranks.
But it still played quality passes forward for O'Brien to score again in the 77th minute and clinch the 4-1 result.
''It was never a 4-1 result. We played some really good football,'' Caversham coach Horner said.
Referring to the three goals conceded between the 31st and 37th minutes, he said: ''We just lost our heads a bit during that period.''
Cashmere's John Brown was obviously delighted to win the SIC trophy for the second successive time, last time beating Dunedin Technical 4 2 on penalties after extra time in 2013.
''We had some inspiring performances out there,'' he said, comparing the skills of Clapham, the deceptive power of Oxley, and midfielder Barton's non stop energy, ''but you can't ignore a striker like Shawn [O'Brien] who scored a hat trick in his 100th game for our club,'' he said.
''He would have to be our man of the match.''
Mainland Football chief executive Julian Bowden was at the match and told the Otago Daily Times he was keen to expand the present single game South Island Championship play off.
Bowden, Cashmere coach Brown and Caversham's Horner are all of the same opinion that increased football contact between Christchurch and Dunedin would be beneficial, and provide an important stepping stone between regional and national leagues.
SI Championship
The scores
Cashmere 4
Shawn O'Brien 3, own goal
Caversham 1
Lewis Jackson
Halftime: 3-0
