The chocolate maker premiered its Christmas TV ad on Saturday (7 November), and it will be running throughout November.
The video shows 24 numbered trucks, each parked to form a giant advent calendar, making their way across Britain.
Each truck will arrive in a new location on each day between 1 and 24 December. The video uses the Thunderbirds theme tune, as the brand looks to build excitement and anticipation. Locations will be announced shortly before their arrival, with social media being used to spread the word locally.
The PR agency Golin is working closely with the advertising firm Fallon on the events at each of the vans' destinations. Three events that have a particularly strong PR element to them will be handled by Golin primarily, the agency told PRWeek.
Claire Low, marketing manager at Cadbury parent firm Mondelèz International, said: "Cadbury has a well-loved place in family homes during the festive period and has been bringing joy to the Christmas Countdown with its advent calendars for more than 50 years.
"Inspired by this, we created the ultimate advent calendar that delivers joy in a way that only Cadbury can at Christmas. Don’t forget to keep your eyes peeled in case a Cadbury trucks opens its doors near you."