Clitheroe suffered only their second defeat of the season on Saturday, but retained their Houldsworth Ribblesdale League title with two games to spare.
Great Harwood kept alive their hopes of runners-up spot with a three-run win over their Chatburn Road visitors.
But Clitheroe collected sufficient points to ensure a third successive senior league crown.
Read are the only other side, between 2002-04, to have completed a hat-trick.
Clitheroe have also been confirmed as Division One champions.
Joey Hawke top scored with 50 as Harwood recovered from 38-6 to reach 112 all out. Clitheroe appeared on course for a 19th league win as they progressed to 80-4, until a late slump saw them slip to 109.
Read, who entertain Harwood in the final game of the campaign, sat out the first part of the weekend double header, before, on Sunday, taking on the champions.
Clitheroe racked up a total of 288-7, as Neil Bolton hit 103, and Guneratne made 94.
In reply, Read were dismissed for 122 as Guneratne completed a man of the match display with 8-57.
Clitheroe host Whalley in the final game of the season on Saturday.
Ribblesdale Wanderers announced prolific South African Ryan Canning will be their professional in 2016, and were then knocked over for 32 in a nine-wicket defeat at home to Padiham.
It also led to an ironic tweet to Earby – bowled out for 17 last week and 30 on Saturday – saying: “Fancy a game? Think we would put on a good show!”
While Canning is staying, Salesbury said farewell to 35-year-old Sri Lankan star, Susantha Pradeep. Four years after a debut of 62 and 5-57, ‘Susa’ marked his last game for the Red Caps by claiming his 250th wicket and hitting the winning runs in a six-wicket win over Edenfield.
Edenfield were dismissed for 75 – with Andrew Mercer taking 7-40, taking him to 75 league wickets for the season.
Whalley, well safe of a relegation/promotion play-off, beat Oswaldtwistle Immanuel by five wickets after bowling their opponents out for 58.
Simon Gorton took 5-9 and now has 82 league wickets.