The three-year-old created a 20-1 surprise in the mile event following on from victory at the Curragh in May.
He had previously finished fourth over a mile and a quarter in April but Morgan expects Roca Tumu to prove more able over the trip, although he could run in new silks next time.
“I’m not sure if you’ll see him in the same colours this season as there’s offers in for him,” she said. “I’d have no doubts about him getting a mile and a quarter as it took Billy (Lee, jockey) nearly five furlongs to pull him up.
“He’s only learning about the trip and a stiff mile looked like it suited him best.
“I’d had him in a Derby trial. However, he didn’t run due to a stone bruise, but I always thought he was of that sort of standard.”
Roca Tumu is owned by a syndicate of the same name and was bred by one of the members.
Morgan added: “Tommy Murphy heads up the syndicate and his father Tommy was champion jockey (in 1978). He has Roca Tumu’s mother (Lucy Diamonds) in foal to Footstepsinthesand at the minute.”
Meanwhile The Lark could finish only fifth as Pacific Rim took the honours in the Abu Dhabi Prix de Malleret at Saint-Cloud yesterday.
A fine third in the Investec Oaks at Epsom at the end of May, Michael Bell’s filly was due to run in the Ribblesdale Stakes at Royal Ascot on Thursday, but was withdrawn by connections on account of the drying conditions.
Instead sent to France for this Group Two assignment, the three-year-old was smartly away from the stalls but was soon taken back by Jamie Spencer.
The 5-2 joint-favourite travelled powerfully towards the rear of the field rounding the home turn, but did not pick up immediately. When she did get going, it was all too late.
Main market rival Ferevia also made late headway, but was well held in fourth in the hands of Olivier Peslier.
The Mikel Delzangles-trained Pacific Rim (11-2) was never too far off the speed under Umberto Rispoli and completed the hat-trick in fine style following wins in lesser company at Maisons-Laffitte and Longchamp.
Chalnetta and Orion Love were second and third respectively.
Bell said: ``There was no pace and she got shuffled back. She was six lengths behind turning for home and that's where she finished.
“I don’t know what they are calling the ground officially, but it’s genuine good ground at best for her.
“There is no mud on the horses hooves or fetlocks when they’re coming in. I’m afraid it was a bit of a non-event as there was no pace, she was trapped on the rail with nowhere to go and the die was cast.
“The style of the race was all wrong for her, but we live to fight another day. There are no immediate plans.”
The other British runner in the 10-strong field was Mick Channon’s Contradict, but she could beat only one home in the hands of Ryan Moore.
* Paul Hanagan will return to action later in the week after escaping serious injury in a fall at Royal Ascot on Saturday. The rider suffered a nasty tumble after his mount Ektihaam slipped on the bend in the Hardwicke Stakes. Hanagan went for X-rays on his upper arm following his fall but his agent Richard Hale reports there to be no serious damage.