Ha!! I lived in the UK in the early 1990s and knew people who participated in that. Even knew a couple people who actually got to take the free flights to New York, plus some others who got screwed. (Apparently tens of thousands of people got hosed and never saw their free flights.)

I read in a marketing industry magazine many years later how this one promotion vastly changed the perception of Hoover as a brand and altered the trajectory of the entire vacuum industry even beyond the UK. In the 80's, Hoover was practically a monopoly. By the 90's, there was serious visceral hate for this company and several new entrants ripping substantial market share away from them. (Dyson being one.)

I also saw a more-lighthearted piece about how secondhand stores and rummage sales were awash in cheap Hoover vacuums for years afterward. People bought hundreds of thousands of them just for this promo and a year later they were everywhere for 20 quid.