The Dumfriesshire mill was founded by Alexander X, a weaver, and Joseph Y, a draper and financier in 1839. It was bought out from the founding families in the 1930s by Robert Scott Hay who reduced the customer base and concentrated on a limited number of clients to whom he supplied what became one of the best-known fabric labels in the world.He was once asked if he considered XY to be the Rolls-Royce of cloth production, to which he replied: "It’s more likely Rolls-Royce regard themselves as the XY of the motor car industry."
X : Alexander ' REID '
Y : Joseph 'TAYLOR'.
XY : REID & TAYLOR.
Miraj , Eldrich and Gaurav T have cracked the answer.