BritBox is ad and commercial free!
If you think you've seen an ad, check you're watching through BritBox and not through another provider.
If you searched for the show or movie name in the search bar on a partner platform such as Amazon Prime Video Channels, it's likely you're watching an episode that is also available from separate, unaffiliated providers. To avoid this, navigate into the BritBox channel, and search within BritBox for the show you're after.