Jim Tweedie was a turner for Wm. Sinclair and Hugh MacPherson during the 1960's before going out on his own in the 1970's to form Inveran House. 

It is very difficult to distinguish the three makes from each other.  Tweedie drones are very full sounding and the bass drone is magnificent.
Makers of Old Bagpipe Place Home
The Bagpipe Place Museum