The winner of five races on the level when trained by Sir Mark Prescott, the son of Azamour was snapped up for 80,000 guineas last October, but has taken a while to find his feet since switching codes.
He was narrowly beaten on his hurdling debut at Taunton in December, disappointed over a longer trip at Ludlow the following month and was a well-beaten third on his latest visit to this track almost three weeks ago.
However, the 5/1 shot travelled strongly in the Bathwick Tyres Bath Handicap Hurdle and moved up to challenge 7/4 favourite Wishfull Dreaming when the latter crashed out two flights from the finish.
Hint Of Mint also came to grief at the same obstacle, with Amour De Nuit left in the clear to seal a 19-length success over Paddys Runner.
Twiston-Davies said: "It's great for the owners, who have been plenty patient.
"He's got there in the end and jumped nicely and that's probably the best he's travelled.
"I've called him a few names so far, but with racing he's learnt and he's a bit more mature now.
"It's nice to get on the board with him and hopefully he's on an upward curve."
Nicholls and Twiston-Davies had earlier combined successfully with odds-on favourite High Secret in the Bathwick Tyres Bridgwater Novices' Hurdle.
A winner over the course and distance in January before finishing third in a strong race at Musselburgh, the 4/5 market leader knuckled down to beat Boagrius by half a length after a protracted duel.
"It's not ideal running in a small field when they go no gallop, but I needed a third run so I could run him in a handicap," Nicholls told At The Races.
"The idea was to aim him at the boys' race (conditional jockeys' handicap hurdle) at Aintree on Grand National day, so he'll go there."
There were also doubles on the day for trainer Emma Baker and jockey James Banks.
Back My Midnight (9/1) jumped and galloped his rivals into the ground to land the Bathwick Tyres Handicap Chase.
Stablemate Bajardo (8/1) then won a dramatic Bathwick Tyres Taunton Handicap Chase, in which Leg Lock Luke looked set for victory but jinked on the run-in and unseated Tom O'Brien.
Banks said of Back My Midnight: "He's done it well. He's not the easiest as he's very hard on himself early doors.
"You'd like him to get further in time, but he likes to get on with it and two miles seems to be his trip."
The Harry Fry-trained Bags Groove (1/3 favourite) landed the opening novice hurdle under Noel Fehily, who gave up his remaining rides as he was unwell, while Kim Bailey's Milord (11/2) ruled the roost in the concluding handicap hurdle.
