I zoomed in on a good photo of the former Castle Vaults Public House from around 1910 or so and noticed two crests engraved into the stonework.
The one at Glasgow Road most definitely is the logo of the Castle Brewery, identified by the Castle Logo, and the business of course which gave its name to nearby Castle Park at Forrest Street.
The Castle Brewery was commissioned in 1900 by G. & J. Maclachlan to replace the Castle Brewery in Glagow, which had become too small to cope with demand. The brewery was completed in 1901, and Duncan Forbes, George Maclachlan’s brother-in-law, was appointed the manager. The brewery closed in 1966, following the takeover of Maclachlans Ltd in 1960 by J. & R. Tennent Ltd.
The other more ornate crest facing on to John Street is more problematic. I’m not sure what it is. I’ll be writing about this side of Glasgow Road soon, but thought I’d ask here if anybody knows what it signifies?