The judge in a court case involving two groups called Blue has been demonstrating his knowledge of the finer points of the pop and rock world.
The "old" Blue members are suing the boy band over their name
Mr Justice Hugh Laddie is in charge of the case in which pop act Blue are being sued by a 1970s rock band of the same name.
The original Blue want to prevent them from using the name, saying their own career and reputation is being damaged.
They are suing the contemporary boy band and their label EMI/Virgin, for up to £5m.
My clients were a boy band in the 1970s
As proceedings began at the High Court, Mr Justice Laddie defied the image of Britain's crusty, out-of-touch judiciary with some pithy examination of counsel.
The judge - known for his broad taste in music - appeared surprised when the older band's barrister said their reputation was being threatened.
"Are you seriously saying that fans of one group would mistake one for the other?" he asked Charles Purle QC.
There is somewhat a difference of appearance. One is aged like you and me, the other is a boy band
"There is somewhat a difference of appearance. One is aged like you and me, the other is a boy band."
Mr Purle said: "My clients were a boy band in the 1970s."
The judge replied: "Oh no. Boy band is a style of music that is a bit more recent than the Charleston."
Members of the original group, including brothers Hugh and David Nicholson and Ian MacMillan, are now in their 50s and based in Scotland.
The younger Blue have had three number one singles since 2001
Elder brother Matt Nicholson, manager of The Record Label, which handles the group, says EMI/Virgin has treated them with "arrogance and contempt".
The group say EMI/Virgin knew of their existence before the boy band's rise to fame.
The contemporary Blue - Duncan James, Anthony Costa, Lee Ryan and Simon Webbe - insist there is "no merit" in the case against them.
They have achieved three UK number one singles, including a collaboration with Sir Elton John on his song Sorry Seems To Be The Hardest Word.
Sir Elton is expected to be called to give evidence, to confirm that the first Blue were signed to his label, Rocket, and produced their album, Another Night Time Flight.