Although both sides created chances throughout, Peel were simply ruthless in front of goal when it mattered, registering a three-goal lead come half-time, adding another trio after the break.
Record 13-time finalists and seven-time winners Royal scored their double in the closing stages.
On six minutes, the westerners opened the scoring when Eleanor Gawne curled in an in-swinging corner which eluded a forest of players before finding the net.
Royal responded with Holly Stephens dropping an effort just over the target, but with 19 minutes on the lock Peel struck again. Gawne turned provider, slipping a through-ball to Louise Gibbins who escaped the attentions of the opposing back four and struck to the top right of the goal.
Chances arrived for both sides as Kayleigh Georgeson hit the woodwork and Stephens forced a good save from Kayleigh Greggor.
Then Peel made Royal pay for missing those chances, clocking up a three-goal lead just before half-time when Kym Hicklin’s back pass to goalkeeper Kerri Williams was intercepted by Becky Corkish who stroked the ball into an unguard net.
After a break, the westerners strengthened their grip further with a fourth. After some good work from Jenny Metcalfe along the left, she cut inside and set up Mica Santos who barged her way through the defence and placed the ball home.
Just before the hour mark, the Sunset City side registered their fifth. Following another move on the left, Gawne’s cut-back on the bye-line found Leah Clegg whose effort was intercepted by Georgeson who accidentally steered the ball into her own net.
On 63 minutes, Peel should have extended their lead further when Clegg was brought down in the penalty area and a spot-kick was awarded. Normally you could bet your mortgage that Gawne would score, but her first attempt was superbly parried and the rebound flashed over the crossbar.
Clegg nearly got on the scoresheet when her effort was saved following another excellent Gawne through ball, but on 75 minutes the Douglas Road side managed to get their sixth of the afternoon when Gawne’s corner was met by Corkish who applied the important touch to guide home.
Royal never gave up though and went close when Rebecca Cole’s effort struck the post, before Sarah O’Reilly cleared the danger and Stephens steered wide from close range following Leah Callow’s cross.
On 84 minutes, the Ballafletcher side finally got on the scoresheet when Cole raced down the left and passed inside for Stephens to sweep home from six yards.
Two minutes later, the Whites struck again following an excellent cross-field pass when Cole’s initial effort was parried but she made sure at the second attempt.
But these proved mere consolations as Peel replicated their success of the 2015-16 season, clinching the league and FA Cup double.