The Royal Canadian Naval Volunteer Reserve
The adjacent plaque was the first created by the Toronto Historical Board, and was installed in 1969 on an earlier building on the site. It marks the first place in Toronto where citizens were recruited and trained by the Royal Canadian Naval Volunteer Reserve (RCNVR). During the Second World War, the RCNVR's 'citizen sailors' became the backbone of the Canadian Navy, the third largest among the Allied Forces. Through the Korean War and into the present, reservists from Toronto have continued to serve their country. The original plaque was restored to celebrate the 100th anniversary of the Canadian Navy.
Plaque via Alan L. Brown's site Toronto Plaques. Full page here.