Watercolour portrait

Having not done too many portraits with watercolour l have set myself the challenge of one every week during my portrait 'drawing' class.  I am quite pleased with this given that l only had 35 minutes to do it in.  I know who it is but l don't think anyone else would recognise the man himself from this particular picture!!  The tutor would say in her kindly way... there is an elusive (could be illusive!?) likeness... leaving me wondering!! What  l have learned over the years is that if one line or measurement is out... the picture will look like someone else entirely... all very challenging!