Simms Watt logo

Simms-Watts – a British manufacturer of amps and PA.

Seen some from the 1969.. Apparently stopped manufacturing around 1976.

Simms-Watts schematics

http://www.drtube.com/guitamp.htm

Images below from Reverb.com and Gumtree UK

Simms Watt PA 150

Simms Watt serial number