I've never seen a housecoat anything near as classy as this
and stockings and suspenders show, I thought, she had to be going out somewhere OR expecting Gambit to call round
I'd certainly prefer to see her wear it going out, than the suit she wore on her dinner date with Cromwell ...not 'accessorised' properly...ask Gambit
Yeah, well, this is Avengerland, where Steed hangs around his house wearing a suit all day--they don't exactly do sweats.
I suspect she put on her stockings because she was getting ready to go out, but she would have traded the kimono for a different outfit before she did--it really does look like more of a robe. A bit too impractical to wear outside the house, particularly if there was a wind.
I really love the suit she wears on her date with Cromwell, though--it gets across that she's not planning on taking any nonsense from him. Purdey as a character had a slightly different role than the other Avengers girls because she had to be both the "girl" of the group, and be able to be "one of the boys", since she had two male colleagues. So she's very feminine in some ways, but she also cuts her hair short and wears trouser suits as well. The suit reflects that part of her character, one that Joanna was always keen to emphasise, as she wanted Purdey to be very tough and no-nonsense. She hated all the stocking shots, and fought them at every corner. She must have succeeded, because they disappeared in season 2.