From the Wikipedia entry:
The Dukes of Stratosphear was a pseudonym used by the British rock band XTC in the mid to late 1980s, in parallel with XTC's continued musical activities. The project was intended as a homage to 1960s pop and psychedelic music by groups such as the Beatles, The Byrds, The Kinks, The Beach Boys, Pink Floyd and the Pretty Things.
The band only released two records, the EP 25 O'Clock (1985), and the full-length album Psonic Psunspot (1987). The two releases were compiled onto a single CD under the title Chips from the Chocolate Fireball. The Dukes were also mentioned in the credits of XTC's 1986 album Skylarking, where they were thanked for the loan of their guitars.
I bought a copy of this album in a London record shop during the summer of 1985 (at the same time Live Aid was occurring). It's a cherished possession.
I've seen the Dukes' music described as Syd Barrett-era Floyd. That's pretty accurate. One of the really cool things about them was that at least on the first album (25 O'Clock), they recorded using only the technology available to groups in the 1960s. And some critics argue that the members of XTC, free from the pressures of writing "serious" songs, turned in tunes superior to those on official XTC albums of the period. It shouldn't be too much of a surprise, but they even did some videos as The Dukes(!).
This first one is for a great track off of 25 O'Clock called "The Mole from the Ministry." It's the Dukes "rewrite" of "I Am the Walrus." The promotional film appears to be outtakes from Magical Mystery Tour (appropriately enough):
And here is one from Psonic Psunspot titled "You're a Good Man Albert Brown":