From a couple of netfriends:

Not a new story http://www.snopes.com/business/genius/fired.asp Snopes don't quite know the whole of it!

My dad said they used to tell that story about Gordon Selfridge in the 1920s.

Selfridge (of Selfridge's, he was a Yank!) made it a rule that his warehousemen had to have their coats off and their sleeves rolled up, and he used to walk round every part of his store regularly. If he saw a man standing around with his coat on, he'd ask what his pay was, give him a note to collect what he was due from the cashier and sack him.

One day he did this and the man stood looking dumbfounded while Selfridge strutted on, so a foreman explained about the rule and said he was sorry the man had lost his new job so quickly.

But the man said "That's all right mate, I works for Carter Patterson!"

It seems unlikely that Selfridge didn't know there might be other firms' porters and messengers waiting around, but at least in those days people still were paid off in cash!