The aircraft was landing on runway 26L at London-Gatwick Airport at the end of a flight from Barbados. After a stable approach, the crew stated that the conditions became ?quite rough? as the aircraft entered the flare. The aircraft was observed to roll markedly in both directions during the touchdown. The surface wind at the time was 350§/15 kt. Later that morning, when the next flight crew to operate the aircraft were carrying out their pre-flight checks, damage was found on the underside of both engines on the right wing. The evidence indicated that ground contact occurred during the last landing. It had not been suspected by the operating crew at the time and had not been noticed during the intervening maintenance check.s.