I swear by Seeland or Paramo base and mid layers. Seeland supply scandinavian hunters (The Millers out at Midmar sell the stuff) and Paramo supply mountain rescue etc (Hilltrek in Aboyne). Both companies know a thing or two about cold weather clothing.
Hilltrek are starting to produce there own range of fishing clothing based on Ventile and Paramos waterproofing technology. Superb jacket called the Dee Wading Jacket, hopefully they will be doing bank jackets this winter.
Outer garments are either Paramo, good old Army Goretex (i get it free
) or the Prologic Thermo Armour Salopettes and jacket.