The branded bus, which first appeared during the brand's activity last year, will be making its way around the capital, with representatives handing out free samples of tea to members of the public throughout the day.
Brand representatives will visit key London train stations between 8-9.30am, including Waterloo, Charing Cross and Liverpool Street, as well as stations in Birmingham, Leeds and Manchester, to provide commuters with samples of the brand's tea varieties.
A Teapigs Tea Bar is set to take over Finsbury Avenue Square between 10.30am and 2.30pm, where a selection of teas will be available to sip on, and there will be treats to devour.
Finally, from 3-4pm the brand will host a birthday tea party for 30 guests. Partygoers will be picked up from Teapigs’ Tea Bar, where they will receive tea, cake and cocktails. They will then hop aboard its Routemaster bus for a tour of London.
Teapigs plans to give away over 100,000 cups of tea on the day, and more than 200 of its stockists are set to take part.
Tea lovers can follow the day's activities via the #teapigsfreeteaday hashtag.