Acrylic paint on watercolour card - 41.5cm x 29.5cm
Above are some progress shots - 'pologies about the bad quality; they were lit only by one angel-poise lamp - but it gives an idea of how it built up. Some details changed, like the bow tie, but I kept pretty faithful to the original sketch with this one. And yes, his 'tache really was that wonky.
Above is the original sketch, done digitally with Sketchbook Pro.