The pressure is on North Devon to get a win against Sandford this Saturday after a 111-run defeat by Heathcoat that has left them 18 points adrift at the foot of the Premier table.
Pete Randerson and Liam Lewis both scored half-centuries as table-topping Heathcoat made 246 for six in their 50 overs.
Randerson and ex-North Devon player Callum French (28) took the score to 119 for two at drinks. Lewis, Jack Dart (30) and Thompson (27) kept the board ticking over.
North Devon openers Dan Bowser and Jaz Kalsi (26) made little headway against opening bowlers Malcolm Cloete and Jamie Drew. When skipper Jackson Thompson turned to spin, wickets fell regularly.
Thompson (4-15), French (2-28) and Jack Menheneott (3-34) did what was required with the minimum of fuss.
Adrian Ishwerwood (22) and Ben Howe (28) were the only batters to join Kalsi in the 20s as North Devon were bowled out for 135 with 15 overs un-bowled.
Sandford are the first team North Devon have to get past to reach safety. Lose this Saturday and Tom Popham's side could be 30 points adrift.