I thought the Real People were often over looked, their album 'Whats on the Outside' was amazing and they made some class scally/psych/indie singles (open up your mind, window pane)
Richard Hawley is another one for me who is just amazing at what he does and his live shows are stunning. Really over looked, his albums never get the cred they deserve. This new on, 'True Loves Gutter' is epic.
Good call for Shack off a few posters. 'Natalie's Party' and 'Comedy' off HMS Fable are quality.
There was a band a few years back called Delays from Southampton. Their album 'Faded Seaside Glamour' was like The La's album. Class.
Also The Stands from Liverpool, folky rock, pop, psych, indie in 2003. Supported Oasis on a few tours. Never got any credit for the debut album, proper over looked band.