The British duo started on the front row of the grid after an impressive qualifying race performance, and secured second place by the first corner in the main race.
The other Nissan GT-R team, Sumo Power GT, managed to get out front, however during its pitstop the car was involved in an accident resulting in its retirement.
That left the British duo to bring home the win, but a fast driving Aston Martin denied them of the victory, gifting the Nissan drivers a well-deserved second place.
Elsewhere in the field, the no.21 Sumo Power GT Nissan GT-R of David Brabham and Jamie Campbell-Walter finished in ninth place, but the German pairing of Michael Krumm and Lucas Luhr in their GT-R suffered an accident and finished in 14th.
A delighted Richard Westbrook said: ‘It goes without saying that this is a brilliant result for Peter and I personally, for JRM Racing, and for Nissan.’
The next round of the 2011 FIA GT1 World Championship is Zolder, Belgium, April 8-10.