The Backyardigans is a Canadian-American television series that aired on Nick Jr. from 2004 to 2010. Like Oswald, Wonder Pets!, and Blue's Clues, it was redubbed for the UK market. The theme song for the dub has been uploaded to YouTube, but no full episodes of it have been found, and it's unknown if any episodes were officially released in any way.
Lizzie Waterworth is known to have been the voice of Austin, as he sounds exactly like Horrid Henry. Waterworth, Janet James, Maria Darling and Mia Murphy were the other voices of the Backyardigans. However, Alicia Keys (when she guest starred in Mission to Mars) was not redubbed.
UPDATE 08/13/2017: AJTheFangirl has said that she has a Backyardigans DVD, Cave Party, and it has the UK dub on it. The episodes will be uploaded to YouTube soon.