Unfortunately, it seems to me that a given amount of cloth was available, overall, for suits in three colours for three customers.
There was sufficient cloth for three three piece suits.
It appears to me that the customer with most 'sway' over the tailor ordered himself a natty little number in brown, three piece, with two spare pairs of trousers, and two jackets, one single- one double-breasted. He would no doubt complain that he did not also get plus fours.
The next customer got the same dark blue suit as he had bought last time, though he was not allowed a waistcoat or a spare pair of trousers, and he got home to find it all a little skimpy.
Unfortunately, with the cloth remaining, the final customer had no waistcoat, a rather tight fitting blue grey jacket with Normal Wisdom sleeves, and a pair of shorts. Because these had no seat, and because the jacket had no back, he was advised not to stand up on public transport.