Speyside 2005 Old Cask 104 Signatory Symingtons Choice Speyside Whisky

70cl / 59.3% / Signatory - A 21-year-old single-cask single malt from a mysterious Speyside distillery, by independent bottlers Signatory as part of its Symington’s Choice range. Matured in first-fill oloroso sherry butt #104 and bottled without chill-filtering or added colour. The only hint to the identity of the distillery is an ‘M’ on the label. Who could Signatory possibly be hinting at with that on a rich, sherried Speyside?