Sim was born in Birnam, Perthsire (near Dunkeld). His father was also a fiddler and, from an early age, Alec was taught by James Macintosh, fiddler/composer from Dunkeld. Later, as a postal worker, he went to Aberdeen to work, and there in 1928 he founded the Aberdeen Strathspey & Reel Society.
Sim recorded several 78rpm records for the Beltona label (eight solo releases, plus three as leader of the Aberdeen Strathspey & Reel Society).
I have found four items on sheet music of material either composed or arranged by Sim, "The Wind On the Heath" - arr. Sim (better known as "Hey to Couper"); "The Laverock's
Nest" (comp. Sim); "Sir William Noble's Quickstep" (comp. Sim) "Glen Isla" - a song, written and composed by Sim.
Sir William Noble's Quickstep