For sale is a WEM SL-40 unit, dating from circa 1970s (made in England).
 
These amps acted as a power stage for the PA/ER40 amps, driving a separate pair of columns for extra output.
 
Serviced by Coopersonic Nottingham, who cleaned it, fitted a new conventional mains inlet (rather than having to rely on an elusive Bulgin-style) and replaced one volume pot with a vintage equivalent.
 
Fully functional and comes complete with its original cover (a rare find in its own right).