Quaid-e-Azam

Detachable collars were fashionable in those days because handwashing an entire shirt was an extremely difficult task to accomplish. Due to this reason, only the collars and cuffs of the shirts were regularly laundered while the rest of the shirt was not! The reason why detachable collars became famous is because, in those days, shirts were considered to be an ‘undergarment’ and were always covered up with a suit jacket. With a clean detachable collar, it was enough to make a ‘clean appearance’ on the outside, when wearing a suit, even if a man’s shirt had not been fully washed…. This is somewhat appalling, but in Jinnah’s case, as he was a man who paid enormous attention to personal hygiene, the case might be different. He most likely employed a staff to launder his clothes regularly (although this particular point has not been officially confirmed).
Detachable collar shirts went on a decline when the washing machine was invented, as it made it extremely convenient to launder an entire shirt at once. Furthermore, in the Edwardian era, collars became higher and less comfortable to wear, so eventually the more comfortable collars became more fashionable, which were lower in height and more functional.