AN official Downton Abbey clothing collection will launch later this year. The apparel line will go on sale alongside an extensive range of new merchandise - from beauty products to furniture - launched by NBC Universal and Carnival Films, the producers of the hit television programme.



Despite first airing in the UK in 2010, show bosses wanted to wait until the series was a hit in the US before branching out with their merchandise. Viewing figures didn't really pick up in America until series three - of which the finale drew a record audience of 7.9 million for channel PBS.



"We'll be working across an entire range of products coming out this year. From fashion, apparel and homeware and furniture to wallpapers, beauty products and stationary," confirmed Gareth Nearne, Downton Abbey's executive producer. "Some of these things have been available since 2012 - we publish books and have made a music album, but the more complex products take time."



A fourth series of Downton Abbey is currently being filmed at Highclere Castle in Berkshire, due to be aired in the UK in September 2013. The show will also make its debut in China later this year.



"In retail terms, the first series launched the program and the brand, the second year ratified it and the show didn't even hit its high point in the US until this year when series three ended," said Nearne. "It's very rare for a British drama to have this much retail potential and merchandising value [in the US]."



The period drama, created by Julian Fellowes, is set in the early 1900s. Potential stockists have yet to be named for the merchandise - which will presumably feature ladylike dresses and accessories as seen on characters such as Lady Mary and the Dowager Countess of Grantham (played by Michelle Dockery and Maggie Smith respectively).



"It's a very slow burn the moment you get into retail, it's extremely cautious, it has to test the established brand," Nearne told CNBC. "No one wants to launch products if the show's going to be a flop."