In my opinion, "Six" is one of the most adventurous britpop records of the 90's. It's a pity that Mansun broke up later, actually they recorded 3 albums plus a a large number of EPs. The best of the 3 records positively is "Six" with GREAT influence from the classic psychedelia and also from prog-rock as we know it. This band should appeal any progger who also likes britpop bands like Coldplay. The EPs are very good too with some non-album tracks that are as good as the album tracks, you can find there some live songs and acoustic versions as well.
It would be interesting that some of this britpop bands (Mansun, The Verve, Muse) are included on the Archives, either on the Experimental/Post-Rock category along with Radiohead and Sigur Ros, or with the Prog-Influenced groups.