Most houses have one shoulder bag and a set of variations. Saint Laurent has a genuine range, and the designs come from different eras and different design instincts. The Mombasa dates back to Tom Ford's tenure. Loulou and Niki are Hedi Slimane designs. Le 5 à 7 is from the Anthony Vaccarello period and takes its name from the French expression for a late afternoon assignation. A ysl shoulder bag therefore requires an actual decision, since a Loulou and a Mombasa have almost nothing in common beyond the strap.

The Loulou Medium in matelassé lambskin is the most structured of the soft bags, with a quilted Y pattern and a chain strap. The Kate Medium in grain de poudre is the most formal and the most rigid, with a rectangular body and the Cassandre as a clasp. The Niki Medium in vintage leather is deliberately crumpled and the most casual thing here. Sunset Medium in suede is the middle ground, with a flap and a defined shape. Jamie Shopping in lambskin is a soft, open tote-shaped shoulder bag. Le 5 à 7 Supple Small Hobo and the Mombasa Medium Hobo are the two slouched shapes, with the Mombasa having a distinctive curved horn handle. The Cassandre Pouch on Chain is the smallest and the most evening-facing. Arabica brown appears twice and is the most useful non-black colour here.

If you take one thing away, the Kate is the bag to buy if you want something that stays sharp and the Niki is the one to buy if you like a bag that ages. Grain de poudre on the Kate is a fine-grained leather that resists scuffing better than anything else in this range, which makes it the most practical formal bag here. Niki's vintage leather is designed to crease and will look better in two years than it does new. Loulou chain straps are heavy and the bag is weighty before you load it. Suede on the Sunset needs protecting. Mombasa's horn handle is the most distinctive silhouette here and the most tied to a specific era of the house.