- Signalling: I dress more formally than everyone else to make up for the fact I'm less professional in other ways

- No signalling: I dress like everyone else because I am like everyone else

- Countersignalling: I wear ratty old clothes with holes in them, and nobody will dare to question it because I'm the important one here

In old-money settings all three of these things can be true simultaneously, dressing more formally than people outside, just like everyone else inside (in fact expected, to indicate familiarity with the standards of class, and often worn, ratty, old, and comfortable.